work

src/dabmodel/LAMFields/FrozenLAMField.py

@@ -1,43 +0,0 @@
-from typing import Generic, TypeVar, Any, Optional
-
-from .LAMField import LAMField
-from .Constraint import Constraint
-from ..tools import LAMdeepfreeze
-from .LAMField import TV_LABField
-
-
-class FrozenLAMField(Generic[TV_LABField]):
-    """FrozenLAMField class
-    a read-only proxy of a Field
-    """
-
-    def __init__(self, inner_field: LAMField[TV_LABField]):
-        self._inner_field = inner_field
-
-    def validate(self, v: Optional[TV_LABField]):
-        self._inner_field.validate(v)
-
-    @property
-    def doc(self) -> str:
-        """Returns Field's documentation (frozen)"""
-        return LAMdeepfreeze(self._inner_field.doc)
-
-    @property
-    def constraints(self) -> tuple[Constraint]:
-        """Returns Field's constraint (frozen)"""
-        return LAMdeepfreeze(self._inner_field.constraints)
-
-    @property
-    def default_value(self) -> Any:
-        """Returns Field's default value (frozen)"""
-        return self._inner_field.default_value
-
-    @property
-    def value(self) -> Any:
-        """Returns Field's value (frosen)"""
-        return self._inner_field.value
-
-    @property
-    def annotations(self) -> Any:
-        """Returns Field's annotation (frozen)"""
-        return LAMdeepfreeze(self._inner_field.annotations)

src/dabmodel/LAMFields/LAMField.py

@@ -1,83 +0,0 @@
-from typing import Generic, TypeVar, Optional, Any
-from typeguard import check_type, CollectionCheckStrategy, TypeCheckError
-from .LAMFieldInfo import LAMFieldInfo
-from .Constraint import Constraint
-from ..tools import LAMdeepfreeze
-from ..exception import InvalidFieldValue
-
-TV_LABField = TypeVar("TV_LABField")
-
-
-class LAMField(Generic[TV_LABField]):
-    """This class describe a Field in Schema"""
-
-    def __init__(self, name: str, v: Optional[TV_LABField], a: Any, i: LAMFieldInfo):
-        self._name: str = name
-        self._source: Optional[type] = None
-        self._info: LAMFieldInfo = i
-        self._annotations: Any = a
-        self.validate(v)
-        self._default_value: Optional[TV_LABField] = v
-        self._value: Optional[TV_LABField] = v
-        self._constraints: list[Constraint[Any]] = i.constraints
-
-    def add_source(self, s: type) -> None:
-        """Adds source Appliance to the Field"""
-        self._source = s
-
-    @property
-    def doc(self) -> str:
-        """Returns Field's documentation"""
-        return self._info.doc
-
-    def add_constraint(self, c: Constraint) -> None:
-        """Adds constraint to the Field"""
-        self._constraints.append(c)
-
-    @property
-    def constraints(self) -> list[Constraint]:
-        """Returns Field's constraint"""
-        return self._info.constraints
-
-    def validate(self, v: Optional[TV_LABField]):
-
-        try:
-            check_type(
-                v,
-                self.annotations,
-                collection_check_strategy=CollectionCheckStrategy.ALL_ITEMS,
-            )
-        except TypeCheckError as exp:
-            raise InvalidFieldValue(
-                f"Value of Field <{self._name}> is not of expected type {self.annotations}."
-            ) from exp
-
-    @property
-    def default_value(self) -> Any:
-        """Returns Field's default value (frozen)"""
-        return LAMdeepfreeze(self._default_value)
-
-    def update_value(self, v: Optional[TV_LABField] = None) -> None:
-        """Updates Field's value"""
-        self.validate(v)
-        self._value = v
-
-    @property
-    def value(self) -> Any:
-        """Returns Field's value (frozen)"""
-        return LAMdeepfreeze(self._value)
-
-    @property
-    def raw_value(self) -> Optional[TV_LABField]:
-        """Returns Field's value"""
-        return self._value
-
-    @property
-    def annotations(self) -> Any:
-        """Returns Field's annotation"""
-        return self._annotations
-
-    @property
-    def info(self) -> LAMFieldInfo:
-        """Returns Field's info"""
-        return self._info

src/dabmodel/LAMFields/LAMFieldInfo.py

@@ -1,26 +0,0 @@
-from typing import Optional, Any
-from .Constraint import Constraint
-
-
-class LAMFieldInfo:
-    """This Class allows to describe a Field in Appliance class"""
-
-    def __init__(
-        self, *, doc: str = "", constraints: Optional[list[Constraint]] = None
-    ):
-        self._doc: str = doc
-        self._constraints: list[Constraint]
-        if constraints is None:
-            self._constraints = []
-        else:
-            self._constraints = constraints
-
-    @property
-    def doc(self) -> str:
-        """Returns Field's documentation"""
-        return self._doc
-
-    @property
-    def constraints(self) -> list[Constraint[Any]]:
-        """Returns Field's constraints"""
-        return self._constraints

src/dabmodel/__init__.py

@@ -15,9 +15,10 @@ from .__metadata__ import __version__, __Summuary__, __Name__
 
 from .meta.element import ClassMutable, ObjectMutable
 from .element import Element
-from .LAMFields.LAMField import LAMField
-from .LAMFields.LAMFieldInfo import LAMFieldInfo
-from .LAMFields.FrozenLAMField import FrozenLAMField
+from .lam_field.lam_field import LAMField
+from .lam_field.lam_field_info import LAMFieldInfo
+
+# from .LAMFields.FrozenLAMField import FrozenLAMField
 from .appliance import Appliance
 from .feature import Feature
 
@@ -27,7 +28,6 @@ from .exception import (
     MultipleInheritanceForbidden,
     BrokenInheritance,
     ReadOnlyField,
-    NewFieldForbidden,
     NotAnnotatedField,
     ReadOnlyFieldAnnotation,
     InvalidFieldValue,
@@ -38,6 +38,8 @@ from .exception import (
     InvalidFeatureInheritance,
     FeatureNotBound,
     UnsupportedFieldType,
+    NonExistingField,
+    InvalidFieldName,
 )
 
 __all__ = [name for name in globals() if not name.startswith("_")]

src/dabmodel/appliance.py

@@ -9,17 +9,50 @@ class Appliance(IAppliance, metaclass=_MetaAppliance):
     An appliance is a server configuration / image that is built using appliance's code and Fields.
     """
 
+    def validate_schema(self):
+        super().validate_schema()
+        for k in self.__lam_schema__["features"]:
+            self.__dict__[k].validate_schema()
+
+    @classmethod
+    def validate_schema_class(cls):
+        super().validate_schema_class()
+        print(cls.__lam_schema__["features"])
+        for v in cls.__lam_schema__["features"].values():
+            v.validate_schema_class()
+
     def _validate_schema_unknown_attr(self, name: str):
-        print(f"(appliance) _validate_schema_unknown_attr {self}:{name}")
-        print(self.__dict__[name])
         if isinstance(self.__dict__[name], Feature):
-            print("ok")
-            pass
-        else:
-            super()._validate_schema_unknown_attr(name)
+            return
+        super()._validate_schema_unknown_attr(name)
 
     def _validate_schema_missing_attr(self, name: str):
         if name == "features":
             return
-        else:
-            super()._validate_schema_missing_attr(name)
+        super()._validate_schema_missing_attr(name)
+
+    @classmethod
+    def _validate_unknown_field_schema(cls, name: str):
+        if name == "features":
+            return
+        super()._validate_unknown_field_schema(name)
+
+    def _freeze_unknown_attr(self, name: str):
+        print(f"??????????????? {name}")
+        if isinstance(self.__dict__[name], Feature):
+            self.__dict__[name].freeze()
+            return
+        super()._freeze_unknown_attr(name)
+
+    def _freeze_missing_attr(self, name: str):
+        if name == "features":
+            return
+        super()._freeze_missing_attr(name)
+
+    @classmethod
+    def _freeze_unknown_field_schema(cls, name: str):
+        if name == "features":
+            for v in cls.__lam_schema__["features"].values():
+                v.freeze_class()
+            return
+        super()._freeze_unknown_field_schema(name)

src/dabmodel/base_element.py

@@ -1,96 +1,259 @@
-from typing import Any
-from typeguard import check_type, CollectionCheckStrategy, TypeCheckError
+from typing import Any, Self, Dict, Optional
 
-from .exception import ReadOnlyField, InvalidFieldValue, NewFieldForbidden, SchemaViolation
+from typeguard import check_type, CollectionCheckStrategy, TypeCheckError
+from copy import deepcopy
+
+# from .LAMFields.FrozenLAMField import FrozenLAMField
+from .lam_field.lam_field import LAMField, LAMField_Element
+from .exception import ReadOnlyField, SchemaViolation, NonExistingField, InvalidFieldValue
 from .tools import LAMdeepfreeze, is_data_attribute
 
+'''
+class ElementView:
+    __slots__ = ("_vals", "_types", "_touched")
+
+    def __init__(
+        self,
+        values: dict[str, Any],
+        types_map: dict[str, type],
+    ):
+        self._vals: dict[str, Any]
+        self._types: dict[str, type]
+        self._touched: set
+        object.__setattr__(self, "_vals", dict(values))
+        object.__setattr__(self, "_types", types_map)
+
+    def __getattr__(self, name: str) -> Any:
+        """internal proxy getattr"""
+        if name not in self._types:
+            raise NonExistingField(f"Unknown field {name}")
+        return self._vals[name]
+
+    def __setattr__(self, name: str, value: Any):
+        """internal proxy setattr"""
+        if name not in self._types:
+            raise NonExistingField(f"Cannot set unknown field {name}")
+        T = self._types[name]
+
+        try:
+            check_type(
+                value,
+                T,
+                collection_check_strategy=CollectionCheckStrategy.ALL_ITEMS,
+            )
+        except TypeCheckError as exp:
+            raise InvalidFieldValue(f"Field <{name}> value is not of expected type {T}.") from exp
+
+        self._vals[name] = value
+
+    def export(self) -> dict:
+        """exports all proxified values"""
+        return dict(self._vals)
+
+
+class ElementViewCls:
+    __slots__ = ("_vals", "_types", "_touched", "_name", "_module")
+
+    def __init__(
+        self,
+        values: dict[str, Any],
+        types_map: dict[str, type],
+        name: Optional[str] = None,
+        module: Optional[str] = None,
+    ):
+        super().__init__(values, types_map)
+        self._name: str
+        self._module: str
+
+        if name is not None:
+            object.__setattr__(self, "_name", name)
+        if module is not None:
+            object.__setattr__(self, "_module", module)
+
+    @property
+    def __name__(self) -> str:
+        """returns proxified class' name"""
+        return self._name
+
+    @property
+    def __module__(self) -> str:
+        """returns proxified module's name"""
+        return self._module
+
+    @__module__.setter
+    def __module__(self, value: str):
+        pass
+'''
+
 
 class BaseElement:
     __lam_schema__ = {}
     __lam_initialized__ = False
     __lam_class_mutable__ = False
     __lam_object_mutable__ = False
+    __lam_options__ = {}
+    """
+    def get_model_spec(self, name: str, module: str, memo: dict[str, Any]) -> ElementView:
+        # memo[self.__name__] = {}
+        init_fieldvalues = {}
+        init_fieldtypes = {}
+        for k, v in self.__lam_schema__.items():
+            if isinstance(v, LAMField_Element):
+                memo[k] = {}
+                init_fieldvalues[k] = v.value.get_model_spec(memo[k])
+                # clone = v.clone_unfrozen().value
+            elif isinstance(v, LAMField):
+                clone = deepcopy(v.value)
+                init_fieldvalues[k] = clone
+            else:
+                pass
+            init_fieldtypes[k] = v.annotations
+        return ElementView(init_fieldvalues, init_fieldtypes)
 
-    def __setattr__(self, key: str, value: Any):
-        print(f"!guarded_setattr {self} {key} {value}")
+    @classmethod
+    def get_model_spec_cls(cls, memo: dict[str, Any]) -> ElementView:
+        # memo[self.__name__] = {}
+        init_fieldvalues = {}
+        init_fieldtypes = {}
+        for k, v in cls.__lam_schema__.items():
+            if isinstance(v, LAMField_Element):
+                memo[k] = {}
+                init_fieldvalues[k] = v.value.get_model_spec(k, memo[k])
+                # clone = v.clone_unfrozen().value
+            elif isinstance(v, LAMField):
+                clone = deepcopy(v.value)
+                init_fieldvalues[k] = clone
+            else:
+                pass
+            init_fieldtypes[k] = v.annotations
+        return ElementViewCls(init_fieldvalues, init_fieldtypes, cls.__name__, cls.__modules__)
+    """
 
+    def clone_as_mutable_variant(
+        self, *, deep: bool = True, _memo: Dict[int, Self] | None = None
+    ) -> Self:
+        raise NotImplemented()
+
+    @classmethod
+    @property
+    def frozen_cls(cls) -> bool:
+        return not cls.__lam_class_mutable__
+
+    @classmethod
+    @property
+    def mutable_obj(cls) -> bool:
+        return cls.__lam_object_mutable__
+
+    @property
+    def frozen(self) -> bool:
+        return not self.__lam_object_mutable__
+
+    def __setattr__(self, key: str, value: Any) -> None:
         if key.startswith("_"):
             return super().__setattr__(key, value)
 
-        if key not in self.__lam_schema__.keys():
-            raise NewFieldForbidden(f"Can't create new object attributes: {key}")
+        if key not in self.__lam_schema__:
+            raise NonExistingField(f"Can't create new object attributes: {key}")
 
         if not self.__lam_object_mutable__:
             raise ReadOnlyField(f"{key} is read-only")
 
-        try:
-            check_type(
-                value,
-                self.__lam_schema__[key].annotations,
-                collection_check_strategy=CollectionCheckStrategy.ALL_ITEMS,
-            )
-        except TypeCheckError as exp:
-            raise InvalidFieldValue(
-                f"Value of Field <{key}> is not of expected type {self.__lam_schema__[key].annotations}."
-            ) from exp
+        self.__lam_schema__[key].validate(value)
+
         return super().__setattr__(key, value)
 
-    def freeze(self, force: bool = False):
-        print("freeze")
+    def freeze(self, force: bool = False) -> None:
+        print("Freezing instance")
         if self.__lam_object_mutable__ or force:
-            print("freezing !!!!!!!!!!!")
-            self.validate_schema()
+            if self.__lam_object_mutable__:
+                self.validate_schema()
 
-            setSchemaKeys = set([_ for _ in self.__lam_schema__.keys()])
-            setInstanceKeys = set(
-                [_[0] for _ in self.__dict__.items() if is_data_attribute(_[0], _[1])]
-            )
-            for unknown_attr in setInstanceKeys - setSchemaKeys:
-                self._validate_schema_unknown_attr(unknown_attr)
+            setSchemaKeys = set(self.__lam_schema__)
+            setInstanceKeys = {_[0] for _ in self.__dict__.items() if is_data_attribute(_[0], _[1])}
 
-            for unknown_attr in setSchemaKeys - setInstanceKeys:
-                self._validate_schema_missing_attr(unknown_attr)
+            for k_unknown in setInstanceKeys - setSchemaKeys:
+                self._freeze_unknown_attr(k_unknown)
 
-            for attrName in setSchemaKeys & setInstanceKeys:
-                print(f"Freezing {attrName}")
-                object.__setattr__(self, attrName, LAMdeepfreeze(self.__dict__[attrName]))
+            for k_missing in setSchemaKeys - setInstanceKeys:
+                self._freeze_missing_attr(k_missing)
+
+            for k in list(setSchemaKeys & setInstanceKeys):
+                if isinstance(self.__dict__[k], BaseElement):
+                    self.__dict__[k].freeze()
+                else:
+                    object.__setattr__(self, k, LAMdeepfreeze(self.__dict__[k]))
 
             self.__lam_object_mutable__ = False
-        else:
-            print("already frozen")
 
-    def _freeze_unknown_attr(self, name: str):
+    def _freeze_unknown_attr(self, name: str) -> None:
         raise SchemaViolation(f"Attribute <{name}> is not in the schema")
 
-    def _freeze_missing_attr(self, name: str):
+    def _freeze_missing_attr(self, name: str) -> None:
         raise SchemaViolation(f"Attribute <{name}> is missing from instance")
 
-    def validate_schema(self):
-        print("validate_schema")
-        setSchemaKeys = set([_ for _ in self.__lam_schema__.keys()])
-        setInstanceKeys = set(
-            [_[0] for _ in self.__dict__.items() if is_data_attribute(_[0], _[1])]
-        )
+    def validate_schema(self) -> None:
+        print("Validating instance schema")
+        setSchemaKeys = set(self.__lam_schema__)
+        setInstanceKeys = {_[0] for _ in self.__dict__.items() if is_data_attribute(_[0], _[1])}
 
-        for unknown_attr in setInstanceKeys - setSchemaKeys:
-            self._validate_schema_unknown_attr(unknown_attr)
+        for k_unknown in setInstanceKeys - setSchemaKeys:
+            self._validate_schema_unknown_attr(k_unknown)
 
-        for unknown_attr in setSchemaKeys - setInstanceKeys:
-            self._validate_schema_missing_attr(unknown_attr)
+        for k_missing in setSchemaKeys - setInstanceKeys:
+            self._validate_schema_missing_attr(k_missing)
 
-        for attrName in setSchemaKeys & setInstanceKeys:
-            print(
-                f"Validating {attrName}: {self.__dict__[attrName]} / {self.__lam_schema__[attrName].annotations}"
-            )
-            self.__lam_schema__[attrName].validate(self.__dict__[attrName])
-        print("validate_schema done")
+        for k in list(setSchemaKeys & setInstanceKeys):
+            self.__lam_schema__[k].validate_self()
 
-    def _validate_schema_unknown_attr(self, name: str):
+    def _validate_schema_unknown_attr(self, name: str) -> None:
         raise SchemaViolation(f"Attribute <{name}> is not in the schema")
 
-    def _validate_schema_missing_attr(self, name: str):
+    def _validate_schema_missing_attr(self, name: str) -> None:
         raise SchemaViolation(f"Attribute <{name}> is missing from instance")
 
     @classmethod
-    def freeze_class(cls, force: bool = False):
-        pass
+    def freeze_class(cls, force: bool = False) -> None:
+        print("Freezing class")
+        if cls.__lam_class_mutable__ or force:
+            cls.validate_schema_class()
+
+            # class should not have any elements so they are all unknown
+            for k_unknown in {_[0] for _ in cls.__dict__.items() if is_data_attribute(_[0], _[1])}:
+                cls._freeze_unknown_attr_class(k_unknown)
+
+            for k, v in cls.__lam_schema__.items():
+                if isinstance(v, LAMField):
+                    cls.__lam_schema__[k].freeze()
+                else:
+                    cls._freeze_unknown_field_schema(k)
+
+                cls.__lam_class_mutable__ = False
+
+    @classmethod
+    def _freeze_unknown_attr_class(cls, name: str) -> None:
+        raise SchemaViolation(f"Class attribute <{name}> is not in the schema")
+
+    @classmethod
+    def _freeze_unknown_field_schema(cls, name: str) -> None:
+        raise SchemaViolation(f"Unknown field <{name} in the schema> ")
+
+    @classmethod
+    def validate_schema_class(cls) -> None:
+        print("Valisating class schema")
+        # class should not have any elements so they are all unknown
+        for k_unknown in {_[0] for _ in cls.__dict__.items() if is_data_attribute(_[0], _[1])}:
+            cls._validate_unknown_attr_class(k_unknown)
+
+        for k, v in cls.__lam_schema__.items():
+            if isinstance(v, LAMField):
+                v.validate_self()
+            else:
+                cls._validate_unknown_field_schema(k)
+
+    @classmethod
+    def _validate_unknown_attr_class(cls, name: str) -> None:
+        raise SchemaViolation(f"Class attribute <{name}> is not in the schema")
+
+    @classmethod
+    def _validate_unknown_field_schema(cls, name: str) -> None:
+        raise SchemaViolation(f"Unknown field <{name} in the schema> ")

src/dabmodel/exception.py

@@ -4,17 +4,24 @@ class DABModelException(Exception):
     """
 
 
-class FunctionForbidden(DABModelException): ...
+class WrongUsage(DABModelException, RuntimeError):
+    pass
 
 
-class ExternalCodeForbidden(FunctionForbidden): ...
+class FunctionForbidden(DABModelException):
+    """FunctionForbidden Exception class"""
 
 
-class ClosureForbidden(FunctionForbidden): ...
+class ExternalCodeForbidden(FunctionForbidden):
+    """ExternalCodeForbidden Exception class"""
 
 
-class ReservedFieldName(Exception):
-    """DABModelException Exception class
+class ClosureForbidden(FunctionForbidden):
+    """ClosureForbidden Exception class"""
+
+
+class ReservedFieldName(AttributeError, DABModelException):
+    """ReservedFieldName Exception class
     Base Exception for DABModelException class
     """
 
@@ -31,19 +38,13 @@ class BrokenInheritance(DABModelException):
     """
 
 
-class ReadOnlyField(DABModelException):
+class ReadOnlyField(AttributeError, DABModelException):
     """ReadOnlyField Exception class
     The used Field is ReadOnly
     """
 
 
-class NewFieldForbidden(DABModelException):
-    """NewFieldForbidden Exception class
-    Field creation is forbidden
-    """
-
-
-class InvalidFieldAnnotation(DABModelException):
+class InvalidFieldAnnotation(AttributeError, DABModelException):
     """InvalidFieldAnnotation Exception class
     The field annotation is invalid
     """
@@ -73,31 +74,31 @@ class UnsupportedFieldType(InvalidFieldAnnotation):
     """
 
 
-class ReadOnlyFieldAnnotation(DABModelException):
+class ReadOnlyFieldAnnotation(AttributeError, DABModelException):
     """ReadOnlyFieldAnnotation Exception class
     Field annotation connot be modified
     """
 
 
-class InvalidFieldValue(DABModelException):
+class InvalidFieldValue(AttributeError, DABModelException):
     """InvalidFieldValue Exception class
     The Field value is invalid
     """
 
 
-class InvalidFieldName(DABModelException):
+class InvalidFieldName(AttributeError, DABModelException):
     """InvalidFieldName Exception class
     The Field name is invalid
     """
 
 
-class NonExistingField(DABModelException):
+class NonExistingField(AttributeError, DABModelException):
     """NonExistingField Exception class
     The given Field is non existing
     """
 
 
-class SchemaViolation(DABModelException):
+class SchemaViolation(AttributeError, DABModelException):
     """SchemaViolation Exception class
     The Element Schema is not respected
     """
@@ -133,7 +134,7 @@ class FeatureBoundToNonAppliance(DABModelException):
     """
 
 
-class FeatureBoundToIncompatiblegAppliance(DABModelException):
+class FeatureBoundToIncompatibleAppliance(DABModelException):
     """FeatureBoundToWrongAppliance Exception class
     Feature have to be bound to correct appliance
     """

src/dabmodel/feature.py

@@ -4,7 +4,7 @@ from .exception import (
     FeatureAlreadyBound,
     FeatureNotBound,
     FeatureBoundToNonAppliance,
-    FeatureBoundToIncompatiblegAppliance,
+    FeatureBoundToIncompatibleAppliance,
 )
 
 
@@ -26,14 +26,13 @@ class Feature(IFeature, metaclass=_MetaFeature):
         cls.check_appliance_bound()
 
         if not issubclass(appliance_cls, cls.__lam_bound_appliance__):
-            raise FeatureBoundToIncompatiblegAppliance(
+            raise FeatureBoundToIncompatibleAppliance(
                 f"Feature {cls} is bound to an incompatible Appliance {appliance_cls}"
             )
 
     @classmethod
     def bind_appliance(cls, appliance_cls):
-        print(f"BINDING {cls} to {appliance_cls}")
-        if cls.__lam_bound_appliance__ != None:
+        if cls.__lam_bound_appliance__ is not None:
             raise FeatureAlreadyBound(
                 f"Feature {cls} already bound to an Appliance {cls.__lam_bound_appliance__}"
             )

src/dabmodel/interfaces.py

@@ -0,0 +1,41 @@
+from typing import Generic, TypeVar, Dict, Protocol, runtime_checkable
+
+
+TV_Freezable = TypeVar("TV_Freezable")
+
+
+@runtime_checkable
+class FreezableElement(Protocol, Generic[TV_Freezable]):
+
+    def clone_as_mutable_variant(
+        self, *, deep: bool = True, _memo: Dict[int, TV_Freezable] | None = None
+    ) -> TV_Freezable:
+        pass
+
+    def freeze(self, force: bool = False) -> None:
+        pass
+
+    @classmethod
+    def freeze_class(cls, force: bool = False) -> None:
+        pass
+
+    def validate_schema(self) -> None:
+        pass
+
+    @classmethod
+    def validate_schema_class(self) -> None:
+        pass
+
+    @classmethod
+    @property
+    def frozen_cls(cls) -> bool:
+        pass
+
+    @classmethod
+    @property
+    def mutable_obj(cls) -> bool:
+        pass
+
+    @property
+    def frozen(self) -> bool:
+        pass

src/dabmodel/lam_field/lam_field.py

@@ -0,0 +1,170 @@
+from typing import Generic, TypeVar, Optional, Any, Self
+from typeguard import check_type, CollectionCheckStrategy, TypeCheckError
+from copy import deepcopy
+from .lam_field_info import LAMFieldInfo
+from .constraint import Constraint
+from ..tools import LAMdeepfreeze
+from ..exception import InvalidFieldValue, ReadOnlyField
+from ..interfaces import FreezableElement
+
+TV_LABField = TypeVar("TV_LABField")
+
+
+class LAMField(Generic[TV_LABField]):
+    """This class describe a Field in Schema"""
+
+    def __init__(self, name: str, val: Optional[TV_LABField], a: Any, i: LAMFieldInfo):
+        self._default_value: Optional[TV_LABField]
+        self._value: Optional[TV_LABField]
+        self.__name: str = name
+        self.__source: Optional[type] = None
+        self.__info: LAMFieldInfo = deepcopy(i)
+        self.__annotations: Any = LAMdeepfreeze(a)
+        self.__frozen: bool = False
+        self._frozen_value: Any = None
+        self.__frozen_value_set: True = False
+        self.validate(val)
+        self._init_value(val)
+
+    def _init_value(self, val: Optional[TV_LABField | FreezableElement]):
+        self._default_value: Optional[TV_LABField] = deepcopy(val)
+        self._value: Optional[TV_LABField] = val
+
+    @property
+    def name(self) -> str:
+        return self.__name
+
+    def is_frozen(self) -> bool:
+        return self.__frozen
+
+    def freeze(self):
+        print(f"Freezing field : {self.name}")
+        self.__frozen = True
+
+    def clone_unfrozen(self) -> Self:
+        field = LAMField(self.__name, self._default_value, self.__annotations, self.__info)
+        field.update_value(self._value)
+        return field
+
+    def add_source(self, src: type) -> None:
+        """Adds source Appliance to the Field"""
+        if self.__frozen:
+            raise ReadOnlyField("Field is frozen, cannot add source now")
+        self.__source = src
+
+    @property
+    def doc(self) -> str:
+        """Returns Field's documentation"""
+        return self.__info.doc
+
+    def add_constraint(self, cons: Constraint) -> None:
+        """Adds constraint to the Field"""
+        if self.__frozen:
+            raise ReadOnlyField("Field is frozen")
+        self.__info.add_constraint(cons)
+
+    @property
+    def constraints(self) -> list[Constraint]:
+        """Returns Field's constraint"""
+        return LAMdeepfreeze(self.__info.constraints)
+
+    def validate_self(self):
+        self.validate(self._value)
+
+    def validate(self, val: Optional[TV_LABField]):
+
+        try:
+            check_type(
+                val,
+                self.annotations,
+                collection_check_strategy=CollectionCheckStrategy.ALL_ITEMS,
+            )
+        except TypeCheckError as exp:
+            raise InvalidFieldValue(
+                f"Value of Field <{self.__name}> is not of expected type {self.annotations}."
+            ) from exp
+
+    @property
+    def default_value(self) -> Any:
+        """Returns Field's default value (frozen)"""
+        return LAMdeepfreeze(self._default_value)
+
+    def update_value(self, val: Optional[TV_LABField] = None) -> None:
+        """Updates Field's value"""
+        if self.__frozen:
+            raise ReadOnlyField("Field is frozen")
+        self.validate(val)
+        self._value = val
+        self.__frozen_value_set = False
+
+    @property
+    def value(self) -> Any:
+        """Returns Field's value (frozen)"""
+        if self.__frozen:
+            return self.frozen_value
+        else:
+            return self.raw_value
+
+    @property
+    def raw_value(self) -> Optional[TV_LABField]:
+        """Returns Field's value"""
+        if self.__frozen:
+            raise ReadOnlyField("Field is frozen")
+        return self._value
+
+    def _generate_frozen_value(self):
+        self._frozen_value = LAMdeepfreeze(self._value)
+
+    @property
+    def frozen_value(self) -> Any:
+        if not self.__frozen_value_set:
+            self._generate_frozen_value()
+            self.__frozen_value_set = True
+        return self._frozen_value
+
+    @property
+    def annotations(self) -> Any:
+        """Returns Field's annotation"""
+        return self.__annotations
+
+    @property
+    def info(self) -> LAMFieldInfo:
+        """Returns Field's info"""
+        return self.__info
+
+
+class LAMField_Element(LAMField[FreezableElement]):
+
+    def _init_value(self, val: Optional[FreezableElement]):
+        self._default_value = deepcopy(val)
+        self._default_value.freeze()
+        self._value = val.clone_as_mutable_variant()
+
+    def validate(self, val: Optional[FreezableElement]):
+        super().validate(val)
+        if val is not None:
+            print(val)
+            val.validate_schema()
+
+    @property
+    def default_value(self) -> Any:
+        return self._default_value
+
+    def update_value(self, val: Optional[FreezableElement] = None) -> None:
+        super().update_value(val.clone_as_mutable_variant())
+
+    def _generate_frozen_value(self):
+        self._frozen_value = deepcopy(self._value)
+        self._frozen_value.freeze()
+
+
+class LAMFieldFactory:
+    @staticmethod
+    def create_field(
+        name: str, val: Optional[TV_LABField], anno: Any, info: LAMFieldInfo
+    ) -> LAMField:
+        print(f"Constructing a Field for {name} -> {val}")
+        if isinstance(val, FreezableElement):
+            return LAMField_Element(name, val, anno, info)
+        else:
+            return LAMField(name, val, anno, info)

src/dabmodel/lam_field/lam_field_info.py

@@ -0,0 +1,27 @@
+from typing import Optional, Any
+from .constraint import Constraint
+
+
+class LAMFieldInfo:
+    """This Class allows to describe a Field in Appliance class"""
+
+    def __init__(self, *, doc: str = "", constraints: Optional[list[Constraint]] = None):
+        self.__doc: str = doc
+        self.__constraints: list[Constraint]
+        if constraints is None:
+            self.__constraints = []
+        else:
+            self.__constraints = constraints
+
+    def add_constraint(self, constraint: Constraint):
+        self.__constraints.append(constraint)
+
+    @property
+    def doc(self) -> str:
+        """Returns Field's documentation"""
+        return self.__doc
+
+    @property
+    def constraints(self) -> list[Constraint[Any]]:
+        """Returns Field's constraints"""
+        return self.__constraints

src/dabmodel/meta/appliance.py

@@ -1,14 +1,10 @@
 from typing import Any, Type
+from frozendict import frozendict
 from copy import copy
 
-from typeguard import check_type, CollectionCheckStrategy, TypeCheckError
-
-from ..LAMFields.LAMField import LAMField
-from ..LAMFields.FrozenLAMField import FrozenLAMField
-from .element import _MetaElement
+from .element import _MetaElement, get_mutable_variant
 from ..feature import Feature
 from ..exception import InvalidFieldValue, InvalidFeatureInheritance, InvalidFieldName
-from ..tools import LAMdeepfreeze
 
 
 class _MetaAppliance(_MetaElement):
@@ -22,7 +18,7 @@ class _MetaAppliance(_MetaElement):
         name: str,
         bases: tuple[type[Any], ...],
         namespace: dict[str, Any],  # pylint: disable=unused-argument
-        extensions: dict[str, Any],
+        stack_exts: dict[str, Any],
     ) -> None:
         """
         Appliance-specific pre-check: ensure the `features` slot exists in schema.
@@ -30,7 +26,7 @@ class _MetaAppliance(_MetaElement):
         Copies the parent's `features` mapping when inheriting to keep it per-class.
         """
 
-        super().check_class(name, bases, namespace, extensions)  # type: ignore[misc]
+        super().check_class(name, bases, namespace, stack_exts)  # type: ignore[misc]
 
         if "features" not in namespace["__lam_schema__"]:
             namespace["__lam_schema__"]["features"] = {}
@@ -41,11 +37,12 @@ class _MetaAppliance(_MetaElement):
         name: str,
         base: type[Any],
         namespace: dict[str, Any],
-        extensions: dict[str, Any],
+        stack_exts: dict[str, Any],
     ):
-        super().inherit_schema(name, base, namespace, extensions)
+        super().inherit_schema(name, base, namespace, stack_exts)
         if "features" in base.__lam_schema__:
-            namespace["__lam_schema__"]["features"] = copy(base.__lam_schema__["features"])
+            namespace["__lam_schema__"]["features"] = {}
+            namespace["__lam_schema__"]["features"].update(base.__lam_schema__["features"])
 
     @classmethod
     def process_class_fields(
@@ -53,18 +50,18 @@ class _MetaAppliance(_MetaElement):
         name: str,
         bases: tuple[type[Any], ...],
         namespace: dict[str, Any],
-        extensions: dict[str, Any],
+        stack_exts: dict[str, Any],
     ):
         """
         Like meta.process_class_fields but also stages Feature declarations.
 
         Initializes:
-          extensions["new_features"], extensions["modified_features"]
+          stack_exts["new_features"], stack_exts["modified_features"]
         then defers to the base scanner for regular fields.
         """
-        extensions["new_features"] = {}
-        extensions["modified_features"] = {}
-        super().process_class_fields(name, bases, namespace, extensions)  # type: ignore[misc]
+        stack_exts["new_features"] = {}
+        stack_exts["modified_features"] = {}
+        super().process_class_fields(name, bases, namespace, stack_exts)  # type: ignore[misc]
 
     @classmethod
     def process_new_field(
@@ -74,7 +71,7 @@ class _MetaAppliance(_MetaElement):
         namespace: dict[str, Any],
         _fname: str,
         _fvalue: Any,
-        extensions: dict[str, Any],
+        stack_exts: dict[str, Any],
     ):  # pylint: disable=unused-argument
         """
         Intercept Feature declarations.
@@ -84,22 +81,23 @@ class _MetaAppliance(_MetaElement):
         - Else, if `_fvalue` is a Feature *class*, stage into `new_features`.
         - Otherwise, it is a regular field: delegate to meta.process_new_field.
         """
-        print(f"(appliance) process_new_field: {_fname}")
-        print(namespace["__lam_schema__"]["features"].keys())
-        if _fname == "feature":
+
+        if _fname == "features":
             raise InvalidFieldName("'feature' is a reserved Field name")
-        if _fname in namespace["__lam_schema__"]["features"].keys():
-            print("??a")
+        if _fname in namespace["__lam_schema__"]["features"]:
             if not issubclass(_fvalue, namespace["__lam_schema__"]["features"][_fname]):
                 raise InvalidFeatureInheritance(
                     f"Feature {_fname} is not an instance of {bases[0]}.{_fname}"
                 )
-            extensions["modified_features"][_fname] = _fvalue
+            stack_exts["modified_features"][_fname] = get_mutable_variant(_fvalue)
+            # stack_exts["modified_features"][_fname] = _fvalue
+            namespace[_fname] = stack_exts["modified_features"][_fname]
         elif isinstance(_fvalue, type) and issubclass(_fvalue, Feature):
-            print("??b")
-            extensions["new_features"][_fname] = _fvalue
+            stack_exts["new_features"][_fname] = get_mutable_variant(_fvalue)
+            # stack_exts["new_features"][_fname] = _fvalue
+            namespace[_fname] = stack_exts["new_features"][_fname]
         else:
-            super().process_new_field(name, bases, namespace, _fname, _fvalue, extensions)  # type: ignore[misc]
+            super().process_new_field(name, bases, namespace, _fname, _fvalue, stack_exts)  # type: ignore[misc]
 
     @classmethod
     def commit_fields(
@@ -108,7 +106,7 @@ class _MetaAppliance(_MetaElement):
         name: str,
         bases: tuple[type[Any], ...],
         namespace: dict[str, Any],  # pylint: disable=unused-argument
-        extensions: dict[str, Any],
+        stack_exts: dict[str, Any],
     ):
         """
         Commit regular fields (via meta) and then bind staged Feature classes.
@@ -117,15 +115,62 @@ class _MetaAppliance(_MetaElement):
           - bind it to `cls` (sets the feature's `_BoundAppliance`),
           - register it under `cls.__LAMSchema__["features"]`.
         """
-        super().commit_fields(cls, name, bases, namespace, extensions)  # type: ignore[misc]
+        super().commit_fields(cls, name, bases, namespace, stack_exts)  # type: ignore[misc]
 
-        for _ftname, _ftvalue in extensions["modified_features"].items():
-            cls.__lam_schema__["features"][_ftname] = _ftvalue
-        for _ftname, _ftvalue in extensions["new_features"].items():
-            _ftvalue.bind_appliance(cls)
-            cls.__lam_schema__["features"][_ftname] = _ftvalue
+        cls.__lam_schema__["features"].update(stack_exts["modified_features"])
+        for v in stack_exts["new_features"].values():
+            v.bind_appliance(cls)
+        cls.__lam_schema__["features"].update(stack_exts["new_features"])
 
-    def finalize_instance(cls: Type, obj, extensions: dict[str, Any]):
+    @classmethod
+    def prepare_initializer_fields(
+        mcs: type["_MetaElement"],
+        cls,
+        name: str,
+        bases: tuple[type[Any], ...],
+        namespace: dict[str, Any],  # pylint: disable=unused-argument
+        init_fieldvalues: dict[str, Any],
+        init_fieldtypes: dict[str, Any],
+        stack_exts: dict[str, Any],
+    ):
+        print(f"prepare_initializer_fields")
+        print(init_fieldvalues)
+        print(init_fieldtypes)
+
+        for k, v in cls.__lam_schema__["features"].items():
+            # mutable_cls = get_mutable_variant(v)
+            init_fieldvalues[k] = v
+            init_fieldtypes[k] = v
+
+    @classmethod
+    def commit_initializer_fields(
+        mcs: type["_MetaElement"],
+        cls,
+        name: str,
+        bases: tuple[type[Any], ...],
+        namespace: dict[str, Any],  # pylint: disable=unused-argument
+        fakecls_exports: dict[str, Any],
+        stack_exts: dict[str, Any],
+    ):
+        print(f"commit_initializer_fields {cls}")
+        from pprint import pprint
+
+        pprint(dir(cls))
+        print(fakecls_exports)
+        for fk, fv in cls.__lam_schema__["features"].items():
+            print(f"Setting value for {fk} from {fakecls_exports[fk]}")
+            # cls.__lam_schema__["features"][k] = fakecls_exports[k]  # .freeze_class()
+
+            for k, v in fv.__lam_schema__.items():
+                # print(f"collected value: {fakecls_exports[fk].__dict__[k]}")
+                v.update_value(fakecls_exports[fk].__getattr__(k))
+            # cls.__dict__[k] = fakecls_exports[k]
+
+    def populate_instance(cls: Type, obj: Any, stack_exts: dict[str, Any], *args: Any, **kw: Any):
+        super().populate_instance(obj, stack_exts, *args, **kw)
+        obj.__lam_schema__["features"] = dict(cls.__lam_schema__["features"])
+
+    def finalize_instance(cls: Type, obj, stack_exts: dict[str, Any]):
         """
         Instantiate and attach all features declared (or overridden) in the instance schema.
         Handles:
@@ -133,33 +178,26 @@ class _MetaAppliance(_MetaElement):
           - Subclass replacements
           - Dict overrides (class + patch dict)
         """
-        for fname, fdef in obj.__lam_schema__.get("features", {}).items():
+        super().finalize_instance(obj, stack_exts)
+        for k, v in obj.__lam_schema__["features"].items():
             # Case 1: plain class or subclass
-            if isinstance(fdef, type) and issubclass(fdef, Feature):
-                inst = fdef()
-                object.__setattr__(obj, fname, inst)
+            if isinstance(v, type) and issubclass(v, Feature):
+                inst = v()
+                inst.freeze()
+                object.__setattr__(obj, k, inst)
 
             # Case 2: (class, dict) → dict overrides
-            elif isinstance(fdef, tuple) and len(fdef) == 2:
-                feat_cls, overrides = fdef
-                inst = feat_cls()
-                for field_name, new_val in overrides.items():
-                    if field_name not in feat_cls.__lam_schema__:
-                        raise InvalidFieldValue(f"Feature '{fname}' has no field '{field_name}'")
-                    field = feat_cls.__lam_schema__[field_name]
-                    field.validate(new_val)
-                    object.__setattr__(inst, field_name, LAMdeepfreeze(new_val))
-                    inst.__lam_schema__[field_name] = FrozenLAMField(
-                        LAMField(field_name, new_val, field.annotations, field._info)
-                    )
-                object.__setattr__(obj, fname, inst)
+            elif isinstance(v, tuple) and len(v) == 2:
+                feat_cls, overrides = v
+                inst = feat_cls(**overrides)
+                inst.freeze()
+                object.__setattr__(obj, k, inst)
+                obj.__lam_schema__["features"][k] = feat_cls
 
             else:
-                raise InvalidFieldValue(
-                    f"Invalid feature definition stored for '{fname}': {fdef!r}"
-                )
+                raise InvalidFieldValue(f"Invalid feature definition stored for '{k}': {fdef!r}")
 
-    def apply_overrides(cls, obj, extensions, *args, **kwargs):
+    def apply_overrides(cls, obj, stack_exts, *args, **kwargs):
         """
         Support for runtime field and feature overrides.
 
@@ -173,7 +211,7 @@ class _MetaAppliance(_MetaElement):
 
         # --- feature overrides ---
         for k, v in list(kwargs.items()):
-            if k in cls.__lam_schema__.get("features", {}):
+            if k in cls.__lam_schema__["features"]:
                 base_feat_cls = cls.__lam_schema__["features"][k]
 
                 # Case 1: subclass replacement (inheritance)
@@ -202,4 +240,16 @@ class _MetaAppliance(_MetaElement):
                 obj.__lam_schema__["features"][k] = v
                 kwargs.pop(k)
 
-        super().apply_overrides(obj, extensions, *args, **kwargs)
+        super().apply_overrides(obj, stack_exts, *args, **kwargs)
+
+    @classmethod
+    def finalize_class(
+        mcs: type["_MetaElement"],
+        cls,
+        name: str,
+        bases: tuple[type[Any], ...],
+        namespace: dict[str, Any],  # pylint: disable=unused-argument
+        stack_exts: dict[str, Any],
+    ):
+        cls.__lam_schema__["features"] = frozendict(cls.__lam_schema__["features"])
+        super().finalize_class(cls, name, bases, namespace, stack_exts)

src/dabmodel/meta/element.py

@@ -1,16 +1,18 @@
-from typing import Optional, TypeVar, get_origin, get_args, Dict, Any, Callable, Type, Union
+from typing import Optional, TypeVar, get_origin, get_args, Any, Type, Union, Dict
 
-from types import FunctionType, UnionType
+from types import FunctionType, UnionType, new_class
 from copy import deepcopy, copy
-
+import sys
+import weakref
 import inspect, ast, textwrap
 
-from typeguard import check_type, TypeCheckError, CollectionCheckStrategy
 
+from typeguard import check_type, TypeCheckError, CollectionCheckStrategy
+from frozendict import frozendict
 from ..tools import _resolve_annotation, _peel_annotated
-from ..LAMFields.LAMField import LAMField
-from ..LAMFields.LAMFieldInfo import LAMFieldInfo
-from ..LAMFields.FrozenLAMField import FrozenLAMField
+from ..lam_field.lam_field import LAMFieldFactory, LAMField
+from ..lam_field.lam_field_info import LAMFieldInfo
+
 from ..defines import ALLOWED_HELPERS_MATH, ALLOWED_HELPERS_DEFAULT, ALLOWED_MODEL_FIELDS_TYPES
 from ..base_element import BaseElement
 
@@ -29,16 +31,153 @@ from ..exception import (
     InvalidInitializerType,
     IncompletelyAnnotatedField,
     UnsupportedFieldType,
+    WrongUsage,
 )
 
-
-class IElement(BaseElement): ...
+# Cache per base class -> mutable variant
+_MUTABLE_VARIANTS = weakref.WeakKeyDictionary()
 
 
-class IFeature(BaseElement): ...
+def _merge_options(base_opts: tuple, *adds) -> tuple:
+    merged = list(base_opts)
+    for a in adds:
+        if a not in merged:
+            merged.append(a)
+    return tuple(merged)
 
 
-class IAppliance(BaseElement): ...
+class IMutableVariant:
+    pass
+
+
+def get_mutable_variant(base: Type[BaseElement]) -> Type[BaseElement]:
+    """
+    Return a subclass of `base` that behaves the same except that instances
+    are created object-mutable (because the class was defined with options=(ObjectMutable,)).
+    """
+    print(f"____ Walking through: {base}")
+    print(f"bases: {base.__bases__}")
+
+    if base in (IElement, IFeature, IAppliance):
+        return base
+
+    if base.mutable_obj or issubclass(base, IMutableVariant):
+        print("already mutable")
+        return base  # already mutable
+
+    cached = _MUTABLE_VARIANTS.get(base)
+    if cached:
+        print("cached")
+        return cached
+
+    meta = type(base)  # keep the same metaclass
+    base_opts = getattr(base, "__lam_options__", ())
+    new_opts = _merge_options(base_opts, ObjectMutable, ClassMutable, _MutableClone)
+
+    # Recursively lift each direct base
+    lifted_bases = []
+    root_base: Optional[type[BaseElement]] = None
+    for b in base.__bases__:
+        if b in (IElement, IFeature, IAppliance):
+            if root_base:
+                raise BrokenInheritance(
+                    f"Multiple exclusive root bases (previous {root_base}, now {b}"
+                )
+            else:
+                root_base = b
+        elif b is BaseElement:
+            raise BrokenInheritance("BaseElement must not be used")
+        elif issubclass(b, IMutableVariant):
+            lifted_bases.append(b)
+        elif issubclass(b, BaseElement) and b is not BaseElement:
+            lifted_bases.append(get_mutable_variant(b))
+    print(f"lifted_bases: {lifted_bases}")
+
+    # Keep original behavior (inherit from C), AND attach lifted base variants
+    if len(lifted_bases) == 0:
+        if root_base is None:
+            raise BrokenInheritance("inheritance root not found")
+        bases = (root_base,)
+    else:
+        bases = tuple(lifted_bases) + (base,)  # ensures B' is subclass of B and A'
+
+    if IMutableVariant not in bases:
+        bases = bases + (IMutableVariant,)
+
+    name = f"{base.__name__}__Mutable"
+
+    def body(ns: dict[str, Any]) -> None:
+        ns["__module__"] = base.__module__
+        ns["__annotations__"] = base.__annotations__
+        # ns["__lam_class_mutable__"] = True
+        # ns["__lam_object_mutable__"] = True
+        ns["__qualname__"] = f"{base.__qualname__}__Mutable"
+        ns["__doc__"] = f"Mutable runtime variant of {base.__qualname__}"
+        for fname, fval in base.__lam_schema__.items():
+            if isinstance(fval, LAMField):
+                # v = getattr(base, fname)
+                ns[fname] = fval.clone_unfrozen().value
+
+    # IMPORTANT: pass options via kwds so your meta receives them
+    print(f"CREATING {name}")
+    variant = new_class(
+        name,
+        bases,
+        {"metaclass": meta, "options": new_opts},
+        body,
+    )
+    # Optional: register for pickling/import
+    sys.modules[base.__module__].__dict__[name] = variant
+
+    _MUTABLE_VARIANTS[base] = variant
+    return variant
+
+
+class IBaseElement(BaseElement):
+
+    def clone_as_mutable_variant(
+        self, *, deep: bool = True, _memo: Dict[int, BaseElement] | None = None
+    ) -> BaseElement:
+
+        if isinstance(self, type):
+            raise WrongUsage("clone_as_mutable_variant can only be applied to an instance")
+
+        if self.mutable_obj:
+            return self  # already mutable
+
+        if _memo is None:
+            _memo = {}
+        sid = id(self)
+        if sid in _memo:
+            return _memo[sid]
+
+        dst_cls = get_mutable_variant(type(self))
+        # Create a fresh instance using the normal constructor path
+        dst = dst_cls()  # your meta will populate defaults; we'll overwrite below
+        _memo[sid] = dst
+
+        for fname, fval in self.__lam_schema__.items():
+            if isinstance(fval, LAMField):
+                v = getattr(self, fname)
+                if isinstance(v, BaseElement):
+                    if deep:
+                        v = v.clone_as_mutable_variant(deep=True, _memo=_memo)
+                    setattr(dst, fname, v)
+                else:
+                    setattr(dst, fname, fval.clone_unfrozen().value)
+
+                # dst.__dict__[fname] = v
+
+        return dst
+
+
+class IElement(IBaseElement): ...
+
+
+class IFeature(IBaseElement): ...
+
+
+class IAppliance(IBaseElement): ...
 
 
 def _check_annotation_definition(  # pylint: disable=too-complex,too-many-return-statements
@@ -81,8 +220,11 @@ def _check_annotation_definition(  # pylint: disable=too-complex,too-many-return
             raise IncompletelyAnnotatedField(f"Annotation requires inner definition: {_type}")
         return all(_check_annotation_definition(_) for _ in _args)
 
-    if isinstance(_origin, type) and issubclass(_origin, IElement):
-        return
+    if isinstance(_origin, type):
+        if issubclass(_origin, IElement):
+            return
+        elif issubclass(_origin, IAppliance):
+            raise UnsupportedFieldType(f"Nested Appliance are not supported: {_type}")
 
     if _type in ALLOWED_MODEL_FIELDS_TYPES:
         return
@@ -183,7 +325,7 @@ class ModelSpecView:
     def __getattr__(self, name: str) -> Any:
         """internal proxy getattr"""
         if name not in self._types:
-            raise AttributeError(f"Unknown field {name}")
+            raise NonExistingField(f"Unknown field {name}")
         return self._vals[name]
 
     def __setattr__(self, name: str, value: Any):
@@ -212,25 +354,58 @@ T_Meta = TypeVar("T_Meta", bound="_MetaElement")
 T_BE = TypeVar("T_BE", bound="BaseElement")
 
 
-class ElementOption:
+class ElementOptions:
     pass
 
 
-class ClassMutable:
+class ClassMutable(ElementOptions):
     pass
 
 
-class ObjectMutable:
+class ObjectMutable(ElementOptions):
+    pass
+
+
+class _MutableClone(ElementOptions):
     pass
 
 
 class _MetaElement(type):
     """metaclass to use to build BaseElement"""
 
-    modified_fields: Dict[str, Any] = {}
-    new_fields: Dict[str, LAMField[Any]] = {}
-    initializer: Optional[Callable[..., Any]] = None
-    __lam_schema__: dict[str, Any] = {}
+    def __new__(
+        mcs: type["_MetaElement"],
+        name: str,
+        bases: tuple[type[BaseElement], ...],
+        namespace: dict[str, Any],
+        **kwargs,
+    ) -> Type:
+        """BaseElement new class"""
+
+        # create a dict to pass contextual arg onto the stack (multithread safe class init)
+        stack_exts: dict[str, Any] = {}
+        stack_exts["kwargs"] = kwargs
+
+        # retrieve options and normalize it (always a tuple)
+        if "options" not in stack_exts["kwargs"]:
+            stack_exts["kwargs"]["options"] = ()
+        elif not isinstance(stack_exts["kwargs"]["options"], tuple):
+            stack_exts["kwargs"]["options"] = (stack_exts["kwargs"]["options"],)
+        else:
+            stack_exts["kwargs"]["options"] = stack_exts["kwargs"]["options"]
+
+        # main class creation pipeline
+        mcs.check_class(name, bases, namespace, stack_exts)
+        mcs.process_class_fields(name, bases, namespace, stack_exts)
+        _cls = super().__new__(mcs, name, bases, namespace)
+        mcs.commit_fields(_cls, name, bases, namespace, stack_exts)
+        mcs.apply_initializer(_cls, name, bases, namespace, stack_exts)
+        mcs.finalize_class(_cls, name, bases, namespace, stack_exts)
+        if not _cls.__lam_class_mutable__:
+            _cls.freeze_class(True)
+        _cls.__lam_initialized__ = True
+
+        return _cls
 
     @classmethod
     def check_class(
@@ -238,7 +413,7 @@ class _MetaElement(type):
         name: str,
         bases: tuple[type[Any], ...],
         namespace: dict[str, Any],  # pylint: disable=unused-argument
-        extensions: dict[str, Any],
+        stack_exts: dict[str, Any],
     ) -> None:
         """
         Early class-build hook.
@@ -249,27 +424,41 @@ class _MetaElement(type):
 
         This runs before the class object is created.
         """
-        print(f"__NEW__ Defining {name}, len(bases) {len(bases)}, with keys { list(namespace)}")
+        from pprint import pprint
+
+        print(f"__NEW__ Defining {name}, bases {bases}")
+        pprint(namespace)
+        pprint(stack_exts["kwargs"]["options"])
 
         if len(bases) > 1:
-            raise MultipleInheritanceForbidden("Multiple inheritance is not supported by dabmodel")
+            if _MutableClone not in stack_exts["kwargs"]["options"]:
+                raise MultipleInheritanceForbidden(
+                    f"Multiple inheritance is not supported by dabmodel: {bases}"
+                )
 
         if len(bases) == 0:
-            raise BrokenInheritance("wrong base class (missing base class")
+            raise BrokenInheritance(f"missing base class")
 
-        if not issubclass(bases[0], BaseElement):
-            raise BrokenInheritance("wrong base class")
+        if not any([issubclass(base, BaseElement) for base in bases]):
+            raise BrokenInheritance(f"wrong base class: {bases}")
 
-        mcs.inherit_schema(name, bases[0], namespace, extensions)
+        # handle schema/fields inheritance
+        mcs.inherit_schema(name, bases[0], namespace, stack_exts)
 
-        # force field without default value to be instantiated (with None)
+        # force annotated fields without value to be still instantiated (with None)
         if "__annotations__" in namespace:
-            for _funknown in [_ for _ in namespace["__annotations__"] if _ not in namespace.keys()]:
-                namespace[_funknown] = None
+            for k_unknown in [_ for _ in namespace["__annotations__"] if _ not in namespace]:
+                namespace[k_unknown] = None
 
         namespace["__lam_initialized__"] = False
-        namespace["__lam_class_mutable__"] = ClassMutable in extensions["kwargs"]["options"]
-        namespace["__lam_object_mutable__"] = ObjectMutable in extensions["kwargs"]["options"]
+
+        # process options
+        namespace["__lam_class_mutable__"] = ClassMutable in stack_exts["kwargs"]["options"]
+        namespace["__lam_object_mutable__"] = ObjectMutable in stack_exts["kwargs"]["options"]
+        namespace["__lam_options__"] = stack_exts["kwargs"]["options"]
+        pprint(stack_exts["kwargs"]["options"])
+        pprint(namespace["__lam_class_mutable__"])
+        pprint(namespace["__lam_object_mutable__"])
 
     @classmethod
     def inherit_schema(  # pylint: disable=too-complex,too-many-branches
@@ -277,9 +466,16 @@ class _MetaElement(type):
         name: str,
         base: type[Any],
         namespace: dict[str, Any],
-        extensions: dict[str, Any],
+        stack_exts: dict[str, Any],
     ):
-        namespace["__lam_schema__"] = copy(base.__lam_schema__)
+        # create a new schema instance
+        namespace["__lam_schema__"] = {}
+        # copy elements from the parent class
+        namespace["__lam_schema__"].update(base.__lam_schema__)
+        # clone element (unfrozen)
+        for k, v in namespace["__lam_schema__"].items():
+            if isinstance(v, LAMField):
+                namespace["__lam_schema__"][k] = namespace["__lam_schema__"][k].clone_unfrozen()
 
     @classmethod
     def process_class_fields(  # pylint: disable=too-complex,too-many-branches
@@ -287,7 +483,7 @@ class _MetaElement(type):
         name: str,
         bases: tuple[type[Any], ...],
         namespace: dict[str, Any],
-        extensions: dict[str, Any],
+        stack_exts: dict[str, Any],
     ):
         """
         Scan the class namespace and partition fields.
@@ -299,43 +495,55 @@ class _MetaElement(type):
 
         Validates annotations and types and removes processed items from `namespace`
         so they won't become normal attributes. Results are staged into:
-          mcs.new_fields, mcs.modified_fields, mcs.initializer
+          stack_exts["new_fields"], stack_exts["modified_fields"], stack_exts["initializer"]
         to be committed later.
         """
-        # iterating new and modified fields
-        mcs.modified_fields = {}
-        mcs.new_fields = {}
-        mcs.initializer = None
+        # Fields Factory
+        stack_exts["modified_fields"] = {}
+        stack_exts["new_fields"] = {}
+        stack_exts["initializer"] = None
         initializer_name: Optional[str] = None
-        for _fname, _fvalue in namespace.items():
-            if _fname == f"_{name}__initializer" or (
-                name.startswith("_") and _fname == "__initializer"
-            ):
-                if not isinstance(_fvalue, classmethod):
-                    raise InvalidInitializerType("__initializer should be a classmethod")
-                mcs.initializer = _fvalue.__func__
+        for k, v in namespace.items():
+            print(f" {name} Processing Field: {k} / {v}")
+            # handling initializer method
+            if k == f"_{name}__initializer" or (name.startswith("_") and k == "__initializer"):
+                if not isinstance(v, classmethod):
+                    raise InvalidInitializerType("__initializer must be a classmethod")
+                stack_exts["initializer"] = v.__func__
                 if name.startswith("_"):
                     initializer_name = "__initializer"
                 else:
                     initializer_name = f"_{name}__initializer"
-            elif _fname.startswith("_"):
+            # skipping protected/private/dunder methods and attributes
+            elif k.startswith("_"):
                 pass
-            elif isinstance(_fvalue, classmethod):
+            # skipping classmethods
+            elif isinstance(v, classmethod):
                 pass
-            elif isinstance(_fvalue, FunctionType):
+            # skipping methods
+            elif isinstance(v, FunctionType):
                 pass
+            # disallowing nested appliances
+            elif isinstance(v, IAppliance) or (isinstance(v, type) and issubclass(v, IAppliance)):
+                raise UnsupportedFieldType(f"Nested Appliance are not supported: {name}:{v}")
+            # supported Fields
             else:
-                print(f"Parsing Field: {_fname} / {_fvalue}")
-                if _fname in namespace["__lam_schema__"].keys():  # Modified fields
-                    mcs.process_modified_field(name, bases, namespace, _fname, _fvalue, extensions)
-                else:  # New fieds
-                    mcs.process_new_field(name, bases, namespace, _fname, _fvalue, extensions)
-        # removing modified fields from class (will add them back later)
-        for _fname in mcs.new_fields:
-            del namespace[_fname]
-        for _fname in mcs.modified_fields:
-            del namespace[_fname]
-        if mcs.initializer is not None and initializer_name is not None:
+                print(f"Staging Field: {k} / {v}")
+                # Modified fields (already in parent's schema as LAMField)
+                if k in namespace["__lam_schema__"] and isinstance(
+                    namespace["__lam_schema__"][k], LAMField
+                ):
+                    mcs.process_modified_field(name, bases, namespace, k, v, stack_exts)
+                # New fields (others)
+                else:
+                    mcs.process_new_field(name, bases, namespace, k, v, stack_exts)
+
+        # removing processed Fields and initializer from namespace (will add them back in the class later)
+        for k in stack_exts["new_fields"]:
+            del namespace[k]
+        for k in stack_exts["modified_fields"]:
+            del namespace[k]
+        if stack_exts["initializer"] is not None and initializer_name is not None:
             del namespace[initializer_name]
 
     @classmethod
@@ -346,20 +554,23 @@ class _MetaElement(type):
         namespace: dict[str, Any],
         _fname: str,
         _fvalue: Any,
-        extensions: dict[str, Any],
+        stack_exts: dict[str, Any],
     ):  # pylint: disable=unused-argument
         """
         Handle a *modified* field declared by a subclass.
 
         Forbids annotation changes, validates the new default value against
-        the inherited annotation, and stages the new default into `mcs.modified_fields`.
+        the inherited annotation, and stages the new default into `stack_exts["modified_fields"]`.
         """
+        # forbid already existing Field's schema from being modified
         if "__annotations__" in namespace and _fname in namespace["__annotations__"]:
             raise ReadOnlyFieldAnnotation(
                 f"annotations cannot be modified on derived classes {_fname}"
             )
+        # validate the new value
         namespace["__lam_schema__"][_fname].validate(_fvalue)
-        mcs.modified_fields[_fname] = _fvalue
+        # stage the new value
+        stack_exts["modified_fields"][_fname] = _fvalue
 
     @classmethod
     def process_new_field(
@@ -369,36 +580,38 @@ class _MetaElement(type):
         namespace: dict[str, Any],
         _fname: str,
         _fvalue: Any,
-        extensions: dict[str, Any],
+        stack_exts: dict[str, Any],
     ):  # pylint: disable=unused-argument
         """
         Handle a *new* field declared on the class.
 
         Resolves string annotations against a whitelist, validates `Annotated[...]`
         payloads (allowing only LAMFieldInfo), checks the default value type,
-        and stages the field as a `LAMField` in `mcs.new_fields`.
+        and stages the field as a `LAMField` in `stack_exts["new_fields"]`.
         """
-        # print(f"New field: {_fname}")
+        print(f"New field: {_fname} / {_fvalue}")
 
-        # check if field is annotated
+        # forbid non annotated field
         if "__annotations__" not in namespace or _fname not in namespace["__annotations__"]:
             raise NotAnnotatedField(f"Every dabmodel Fields must be annotated ({_fname})")
 
-        # check if annotation is allowed
+        # check if annotations' format is correct and save them
         if isinstance(namespace["__annotations__"][_fname], str):
             namespace["__annotations__"][_fname] = _resolve_annotation(
                 namespace["__annotations__"][_fname]
             )
 
+        # effectively checking the value is conform to annotations
         try:
             _check_annotation_definition(namespace["__annotations__"][_fname])
         except InvalidFieldAnnotation:
             raise
         except Exception as ex:
             raise InvalidFieldAnnotation(
-                f"Field <{_fname}> has not an allowed or valid annotation.", ex
-            )
+                f"Field <{_fname}> has not an allowed or valid annotation."
+            ) from ex
 
+        # extracting LAMFieldInfo from Annotated[] annotations
         _finfo: LAMFieldInfo = LAMFieldInfo()
         origin = get_origin(namespace["__annotations__"][_fname])
         tname = (
@@ -409,17 +622,67 @@ class _MetaElement(type):
             if args:
                 if len(args) > 2:
                     raise InvalidFieldAnnotation(f"Field <{_fname}> had invalid Annotated value.")
-                if len(args) == 2 and not isinstance(args[1], LAMFieldInfo):
+                if len(args) == 2 and not issubclass(type(args[1]), LAMFieldInfo):
                     raise InvalidFieldAnnotation(
                         "Only LAMFieldInfo object is allowed as Annotated data."
                     )
 
                 _finfo = args[1]
-
-        mcs.new_fields[_fname] = LAMField(
+        # stage the new field
+        stack_exts["new_fields"][_fname] = LAMFieldFactory.create_field(
             _fname, _fvalue, namespace["__annotations__"][_fname], _finfo
         )
 
+    @classmethod
+    def commit_fields(
+        mcs: type["_MetaElement"],
+        cls,
+        name: str,
+        bases: tuple[type[Any], ...],
+        namespace: dict[str, Any],  # pylint: disable=unused-argument
+        stack_exts: dict[str, Any],
+    ):
+        """
+        Commit staged fields into the class schema (`__lam_schema__`).
+
+        - For modified fields: copy the parent's LAMField, update its value.
+        - For new fields: set the freshly built LAMField and record its source.
+        """
+
+        # updating values of modified fields
+        for k, v in stack_exts["modified_fields"].items():
+            cls.__lam_schema__[k].update_value(v)
+
+        # registering new fields
+        for k, v in stack_exts["new_fields"].items():
+            v.add_source(cls)
+            cls.__lam_schema__[k] = v
+
+    @classmethod
+    def prepare_initializer_fields(
+        mcs: type["_MetaElement"],
+        cls,
+        name: str,
+        bases: tuple[type[Any], ...],
+        namespace: dict[str, Any],  # pylint: disable=unused-argument
+        init_fieldvalues: dict[str, Any],
+        init_fieldtypes: dict[str, Any],
+        stack_exts: dict[str, Any],
+    ):
+        pass
+
+    @classmethod
+    def commit_initializer_fields(
+        mcs: type["_MetaElement"],
+        cls,
+        name: str,
+        bases: tuple[type[Any], ...],
+        namespace: dict[str, Any],  # pylint: disable=unused-argument
+        fakecls_exports: dict[str, Any],
+        stack_exts: dict[str, Any],
+    ):
+        pass
+
     @classmethod
     def apply_initializer(
         mcs: type["_MetaElement"],
@@ -427,7 +690,7 @@ class _MetaElement(type):
         name: str,
         bases: tuple[type[Any], ...],
         namespace: dict[str, Any],  # pylint: disable=unused-argument
-        extensions: dict[str, Any],
+        stack_exts: dict[str, Any],
     ):
         """
         Apply the optional `__initializer` classmethod to compute derived defaults.
@@ -438,140 +701,122 @@ class _MetaElement(type):
         class schema's DABFields.
         """
 
-        if mcs.initializer is not None:
-            _check_initializer_safety(mcs.initializer)
+        if stack_exts["initializer"] is not None:
+            # checking initializer function sanity
+            _check_initializer_safety(stack_exts["initializer"])
+
+            # preparing initializer context values
             init_fieldvalues = {}
             init_fieldtypes = {}
-            for _fname, _fvalue in cls.__lam_schema__.items():
-                if isinstance(_fvalue, LAMField):
-                    init_fieldvalues[_fname] = deepcopy(_fvalue.raw_value)
-                    init_fieldtypes[_fname] = _fvalue.annotations
-
+            for k, v in cls.__lam_schema__.items():
+                if isinstance(v, LAMField):
+                    # clone = v.clone_unfrozen().value
+                    clone = deepcopy(v.value)
+                    init_fieldvalues[k] = clone
+                    init_fieldtypes[k] = v.annotations
+            mcs.prepare_initializer_fields(
+                cls, name, bases, namespace, init_fieldvalues, init_fieldtypes, stack_exts
+            )
+            # creating a fake class container to hold the context
             fakecls = ModelSpecView(init_fieldvalues, init_fieldtypes, cls.__name__, cls.__module__)
             # fakecls = cls
+
+            # preparing a fake and safe environment
             safe_globals = {
                 "__builtins__": {"__import__": _blocked_import},
                 **ALLOWED_HELPERS_DEFAULT,
             }
-            # if mcs.initializer.__code__.co_freevars:
+            # if stack_exts["initializer"].__code__.co_freevars:
             #    raise FunctionForbidden("__initializer must not use closures")
+
+            # creating the fake call
             safe_initializer = FunctionType(
-                mcs.initializer.__code__,
+                stack_exts["initializer"].__code__,
                 safe_globals,
-                name=mcs.initializer.__name__,
-                argdefs=mcs.initializer.__defaults__,
-                closure=mcs.initializer.__closure__,
+                name=stack_exts["initializer"].__name__,
+                argdefs=stack_exts["initializer"].__defaults__,
+                closure=stack_exts["initializer"].__closure__,
             )
+            # calling initializer
             safe_initializer(fakecls)  # pylint: disable=not-callable
 
-            for _fname, _fvalue in fakecls.export().items():
-                field = cls.__lam_schema__[_fname]
-                field.validate(_fvalue)
-                cls.__lam_schema__[_fname] = LAMField(
-                    _fname, _fvalue, field.annotations, field.info
-                )
-
-    def __new__(
-        mcs: type["_MetaElement"],
-        name: str,
-        bases: tuple[type[Any], ...],
-        namespace: dict[str, Any],
-        **kwargs,
-    ) -> Type:
-        """BaseElement new class"""
-
-        extensions: dict[str, Any] = {}
-        extensions["kwargs"] = kwargs
-        if "options" not in extensions["kwargs"]:
-            extensions["kwargs"]["options"] = ()
-        elif extensions["kwargs"]["options"] is not tuple:
-            extensions["kwargs"]["options"] = (extensions["kwargs"]["options"],)
-
-        mcs.check_class(name, bases, namespace, extensions)
-        mcs.process_class_fields(name, bases, namespace, extensions)
-
-        _cls = super().__new__(mcs, name, bases, namespace)
-
-        mcs.commit_fields(_cls, name, bases, namespace, extensions)
-        mcs.apply_initializer(_cls, name, bases, namespace, extensions)
-        mcs.finalize_class(_cls, name, bases, namespace, extensions)
-
-        if not _cls.__lam_class_mutable__:
-            _cls.freeze_class(True)
-        _cls.__lam_initialized__ = True
-
-        return _cls
+            # copying values back to the class
+            fakecls_exports = fakecls.export()
+            for k, v in cls.__lam_schema__.items():
+                if isinstance(v, LAMField):
+                    cls.__lam_schema__[k].update_value(fakecls_exports[k])
+            mcs.commit_initializer_fields(cls, name, bases, namespace, fakecls_exports, stack_exts)
 
     @classmethod
-    def commit_fields(
+    def finalize_class(
         mcs: type["_MetaElement"],
         cls,
         name: str,
         bases: tuple[type[Any], ...],
         namespace: dict[str, Any],  # pylint: disable=unused-argument
-        extensions: dict[str, Any],
+        stack_exts: dict[str, Any],
     ):
-        """
-        Commit staged fields into the class schema (`__lam_schema__`).
+        # freezing the field schema
+        cls.__lam_schema__ = frozendict(cls.__lam_schema__)
 
-        - For modified fields: copy the parent's LAMField, update its value.
-        - For new fields: set the freshly built LAMField and record its source.
-        """
-        for _fname, _fvalue in mcs.modified_fields.items():
-            cls.__lam_schema__[_fname] = deepcopy(bases[0].__lam_schema__[_fname])
-            cls.__lam_schema__[_fname].update_value(_fvalue)
+    def __setattr__(cls, name: str, value: Any):
+        if not hasattr(cls, "__lam_initialized__") or not getattr(cls, "__lam_initialized__"):
+            return super().__setattr__(name, value)
 
-        for _fname, _fvalue in mcs.new_fields.items():
-            _fvalue.add_source(cls)
-            cls.__lam_schema__[_fname] = _fvalue
+        if name.startswith("_"):
+            return super().__setattr__(name, value)
+
+        if name not in cls.__lam_schema__:
+            raise NonExistingField(f"Can't create new class attributes: {name}")
+
+        if not cls.__lam_class_mutable__:
+            raise ReadOnlyField(f"Class is immutable.")
+
+        field = cls.__lam_schema__[name]
+        field.update_value(value)
+        return
+
+    def __getattr__(cls, name) -> Any:
+        if (
+            hasattr(cls, "__lam_initialized__")
+            and getattr(cls, "__lam_initialized__")
+            and name in cls.__lam_schema__
+        ):
+            return cls.__lam_schema__[name].value
+        raise NonExistingField(f"Non existing class attribute: {name}")
 
     def __call__(cls: Type, *args: Any, **kw: Any):  # intentionally untyped
         """BaseElement new instance"""
         obj = super().__call__(*args)
 
-        extensions: dict[str, Any] = {}
+        # create a dict to pass contextual arg onto the stack (multithread safe class init)
+        stack_exts: dict[str, Any] = {}
 
-        cls.populate_instance(
-            obj, extensions, *args, **kw
-        )  # pylint: disable=no-value-for-parameter
-        cls.freeze_instance_schema(
-            obj, extensions, *args, **kw
-        )  # pylint: disable=no-value-for-parameter
-        cls.apply_overrides(obj, extensions, *args, **kw)  # pylint: disable=no-value-for-parameter
-        cls.finalize_instance(obj, extensions)  # pylint: disable=no-value-for-parameter
+        # create instance attributes from schema
+        cls.populate_instance(obj, stack_exts, *args, **kw)
+        cls.apply_overrides(obj, stack_exts, *args, **kw)
+        cls.finalize_instance(obj, stack_exts)
         if not cls.__lam_object_mutable__:
             obj.freeze(True)
         return obj
 
-    def populate_instance(cls: Type, obj: Any, extensions: dict[str, Any], *args: Any, **kw: Any):
+    def populate_instance(cls: Type, obj: Any, stack_exts: dict[str, Any], *args: Any, **kw: Any):
         """
         Populate the new instance with field values from the class schema.
 
         Copies each LAMField.value to an instance attribute (deep-frozen view).
         """
-        for _fname, _fvalue in cls.__lam_schema__.items():
-            if isinstance(_fvalue, LAMField):
-                object.__setattr__(obj, _fname, _fvalue.raw_value)
+        obj.__lam_schema__ = dict(cls.__lam_schema__)
+        for k, v in obj.__lam_schema__.items():
+            if isinstance(v, LAMField):
+                unfrozen_clone = v.clone_unfrozen()
+                obj.__lam_schema__[k] = unfrozen_clone
+                if obj.__lam_object_mutable__:
+                    object.__setattr__(obj, k, unfrozen_clone.value)
+                else:
+                    object.__setattr__(obj, k, unfrozen_clone.frozen_value)
 
-    def freeze_instance_schema(
-        cls: Type, obj: Any, extensions: dict[str, Any], *args: Any, **kw: Any
-    ):
-        """
-        Freeze the instance's schema by wrapping DABFields into FrozenLAMField.
-
-        Creates a per-instance `__lam_schema__` dict where each field is read-only.
-        """
-        inst_schema = copy(obj.__lam_schema__)
-        for _fname, _fvalue in cls.__lam_schema__.items():
-            if isinstance(_fvalue, LAMField):
-                inst_schema[_fname] = FrozenLAMField(_fvalue)
-
-        if "features" in inst_schema:
-            inst_schema["features"] = dict(inst_schema["features"])
-
-        object.__setattr__(obj, "__lam_schema__", inst_schema)
-
-    def apply_overrides(cls, obj, extensions, *args, **kwargs):
+    def apply_overrides(cls, obj, stack_exts, *args, **kwargs):
         """
         Hook for runtime overrides at instance creation.
 
@@ -583,20 +828,19 @@ class _MetaElement(type):
 
         # --- field overrides (unchanged) ---
         for k, v in list(kwargs.items()):
-            if k in cls.__lam_schema__:  # regular field
-                field = cls.__lam_schema__[k]
-                field.validate(v)
-                object.__setattr__(obj, k, v)
-                obj.__lam_schema__[k] = FrozenLAMField(
-                    LAMField(k, v, field.annotations, field.info)
-                )
+            if k in obj.__lam_schema__:  # regular field
+                obj.__lam_schema__[k].update_value(v)
+                if not obj.__lam_object_mutable__:
+                    object.__setattr__(obj, k, obj.__lam_schema__[k].frozen_value)
+                else:
+                    object.__setattr__(obj, k, obj.__lam_schema__[k].value)
                 kwargs.pop(k)
 
         if kwargs:
-            unknown = ", ".join(sorted(kwargs.keys()))
+            unknown = ", ".join(sorted(kwargs))
             raise InvalidFieldValue(f"Unknown parameters: {unknown}")
 
-    def finalize_instance(cls: Type, obj: Any, extensions: dict[str, Any]):
+    def finalize_instance(cls: Type, obj: Any, stack_exts: dict[str, Any]):
         """
         Finalization hook invoked at the end of instance construction.
 
@@ -604,45 +848,8 @@ class _MetaElement(type):
         to the instance. (Example: BaseMetaAppliance instantiates bound Features
         and sets them as attributes on the appliance instance.)
         """
-
-    def __setattr__(cls, name: str, value: Any):
-        if not hasattr(cls, "__lam_initialized__") or not getattr(cls, "__lam_initialized__"):
-            return super().__setattr__(name, value)
-
-        if name.startswith("_"):
-            return super().__setattr__(name, value)
-
-        if name not in cls.__lam_schema__.keys():
-            raise NonExistingField(f"Can't create new class attributes: {name}")
-
-        if not cls.__lam_class_mutable__:
-            raise ReadOnlyField(f"Class Field <{name}> is read only.")
-
-        field = cls.__lam_schema__[name]
-        field.validate(value)
-        cls.__lam_schema__[name] = LAMField(name, value, field.annotations, field.info)
-
-    def __getattr__(cls, name) -> Any:
-        if hasattr(cls, "__lam_initialized__") and getattr(cls, "__lam_initialized__"):
-            if name.startswith("_"):
-                return super().__getattr__(name)
-            if name in cls.__lam_schema__.keys():
-                if cls.__lam_class_mutable__:
-                    return cls.__lam_schema__[name].raw_value
-                else:
-                    return cls.__lam_schema__[name].value
-            else:
-                raise NonExistingField("Non existing class attribute")
-        else:
-            return super().__getattr__(name)
-
-    @classmethod
-    def finalize_class(
-        mcs: type["_MetaElement"],
-        cls,
-        name: str,
-        bases: tuple[type[Any], ...],
-        namespace: dict[str, Any],  # pylint: disable=unused-argument
-        extensions: dict[str, Any],
-    ):
-        pass
+        obj.__lam_schema__ = frozendict(obj.__lam_schema__)
+        if not obj.__lam_object_mutable__:
+            for v in obj.__lam_schema__.values():
+                if isinstance(v, LAMField):
+                    v.freeze()

src/dabmodel/meta/feature.py

@@ -14,12 +14,11 @@ class _MetaFeature(_MetaElement):
         name: str,
         bases: tuple[type[Any], ...],
         namespace: dict[str, Any],  # pylint: disable=unused-argument
-        extensions: dict[str, Any],
+        stack_exts: dict[str, Any],
     ):
-        if "appliance" in extensions["kwargs"]:
-            cls.bind_appliance(extensions["kwargs"]["appliance"])
+        if "appliance" in stack_exts["kwargs"]:
+            cls.bind_appliance(stack_exts["kwargs"]["appliance"])
 
-    def finalize_instance(cls: Type, obj: Any, extensions: dict[str, Any]):
-        print(f"2GOT {cls}: {cls.__lam_bound_appliance__}")
+    def finalize_instance(cls: Type, obj: Any, stack_exts: dict[str, Any]):
         cls.check_appliance_bound()
-        super().finalize_instance(obj, extensions)
+        super().finalize_instance(obj, stack_exts)

src/dabmodel/tools.py

@@ -1,6 +1,6 @@
 """library's internal tools"""
 
-from typing import Union, List, Any, Dict, get_origin, get_args
+from typing import Any, get_origin, get_args
 from uuid import UUID
 from datetime import datetime
 import json

test/test_appliance.py

@@ -1619,7 +1619,7 @@ class ApplianceTest(unittest.TestCase):
             x: int = 1
 
         app = App()
-        with self.assertRaises(dm.NewFieldForbidden):
+        with self.assertRaises(dm.NonExistingField):
             app.y = 2
 
     def test_private_field_allowed(self):
@@ -1906,6 +1906,52 @@ class ApplianceTest(unittest.TestCase):
         app = App()
         self.assertEqual(app.data["nums"], (1, 2))  # frozen tuple after init
 
+    def test_features_field_not_allowed(self):
+        with self.assertRaises(dm.InvalidFieldName):
+
+            class App(dm.Appliance):
+                features: str = ""
+
+    def test_features_field_not_allowed_2(self):
+        with self.assertRaises(dm.InvalidFieldName):
+
+            class App(dm.Appliance):
+                features: dm.Element = dm.Element()
+
+    def test_nested_appliance_not_allowed(self):
+        with self.assertRaises(dm.UnsupportedFieldType):
+
+            class App(dm.Appliance):
+                class NestdApp(dm.Appliance):
+                    pass
+
+    def test_nested_appliance_not_allowed_2(self):
+        class NestdApp(dm.Appliance):
+            pass
+
+        with self.assertRaises(dm.UnsupportedFieldType):
+
+            class App(dm.Appliance):
+                wrong: NestdApp = NestdApp()
+
+    def test_nested_appliance_not_allowed_3(self):
+        class NestdApp(dm.Appliance):
+            pass
+
+        with self.assertRaises(dm.UnsupportedFieldType):
+
+            class App(dm.Appliance):
+                wrong: Optional[NestdApp] = None
+
+    def test_nested_appliance_not_allowed_4(self):
+        class NestdApp(dm.Appliance):
+            pass
+
+        with self.assertRaises(dm.UnsupportedFieldType):
+
+            class App(dm.Appliance):
+                wrong: NestdApp = None
+
 
 # ---------- main ----------
 

test/test_element.py

@@ -340,7 +340,6 @@ class ElementTest(unittest.TestCase):
             elem: E = E(ivalue=45)
 
         a = A()
-
         self.assertIsInstance(a.elem, E)
         self.assertEqual(a.elem.ivalue, 45)
         self.assertEqual(a.elem.get_increment(), 46)
@@ -352,7 +351,6 @@ class ElementTest(unittest.TestCase):
                 cls.elem = cls.elem.increment()
 
         b = B()
-
         self.assertEqual(b.elem.ivalue, 46)
         self.assertEqual(b.elem.get_increment(), 47)
 
@@ -374,27 +372,421 @@ class ElementTest(unittest.TestCase):
 
         with self.assertRaises(dm.FunctionForbidden):
 
-            class B(dm.Element):
+            class C(dm.Element):
                 elem: E = E()
 
                 @classmethod
                 def __initializer(cls):
-                    print("COUCOU")
                     cls.elem = E(ivalue=test_fun())
 
-    def test_mutable_class(self):
+    def test_mutable_class2_newelement_fails(self):
+
+        class E(dm.Element, options=(dm.ClassMutable)):
+            ivalue: int = 43
+
+        with self.assertRaises(dm.NonExistingField):
+            E.test = 123
+        e = E()
+        with self.assertRaises(dm.NonExistingField):
+            e.test = 123
+
+    def test_mutable_class_freeze(self):
 
         class E(dm.Element, options=(dm.ClassMutable)):
             ivalue: int = 43
 
         E.ivalue = 12
         self.assertEqual(E.ivalue, 12)
-
         E.freeze_class()
         self.assertEqual(E.ivalue, 12)
-
+        with self.assertRaises(dm.ReadOnlyField):
+            E.ivalue = 13
+        self.assertEqual(E.ivalue, 12)
         e = E()
         self.assertEqual(e.ivalue, 12)
+        with self.assertRaises(dm.ReadOnlyField):
+            e.ivalue = 14
+        self.assertEqual(e.ivalue, 12)
+
+    def test_mutable_object_freeze(self):
+
+        class E(dm.Element, options=(dm.ObjectMutable)):
+            ivalue: int = 43
+
+        self.assertEqual(E.ivalue, 43)
+        with self.assertRaises(dm.ReadOnlyField):
+            E.ivalue = 13
+        self.assertEqual(E.ivalue, 43)
+        e = E()
+        self.assertEqual(e.ivalue, 43)
+        e.ivalue = 14
+        self.assertEqual(e.ivalue, 14)
+        e.freeze()
+        self.assertEqual(e.ivalue, 14)
+        with self.assertRaises(dm.ReadOnlyField):
+            e.ivalue = 15
+        self.assertEqual(e.ivalue, 14)
+
+    def test_mutable_object_and_class_freeze(self):
+
+        class E(dm.Element, options=(dm.ObjectMutable, dm.ClassMutable)):
+            ivalue: int = 43
+
+        self.assertEqual(E.ivalue, 43)
+        E.ivalue = 13
+        self.assertEqual(E.ivalue, 13)
+        e = E()
+        self.assertEqual(e.ivalue, 13)
+        e.ivalue = 14
+        self.assertEqual(e.ivalue, 14)
+        e.freeze()
+        self.assertEqual(e.ivalue, 14)
+        with self.assertRaises(dm.ReadOnlyField):
+            e.ivalue = 15
+        self.assertEqual(e.ivalue, 14)
+
+    def test_mutable_class_freeze_container(self):
+
+        class E(dm.Element, options=(dm.ClassMutable)):
+            ar_ivalue: list[int] = [43]
+
+        E.ar_ivalue.append(12)
+        self.assertEqual(E.ar_ivalue, [43, 12])
+        E.freeze_class()
+        self.assertEqual(E.ar_ivalue, (43, 12))
+        with self.assertRaises(AttributeError):
+            E.ar_ivalue.append(52)
+        self.assertEqual(E.ar_ivalue, (43, 12))
+        e = E()
+        self.assertEqual(e.ar_ivalue, (43, 12))
+        with self.assertRaises(AttributeError):
+            e.ar_ivalue.append(52)
+        self.assertEqual(e.ar_ivalue, (43, 12))
+
+    def test_mutable_object_freeze_container(self):
+
+        class E(dm.Element, options=(dm.ObjectMutable)):
+            ar_ivalue: list[int] = [43, 54]
+
+        self.assertEqual(E.ar_ivalue, (43, 54))
+        with self.assertRaises(AttributeError):
+            E.ar_ivalue.append(13)
+        self.assertEqual(E.ar_ivalue, (43, 54))
+        e = E()
+        self.assertEqual(e.ar_ivalue, [43, 54])
+        e.ar_ivalue.append(32)
+        self.assertEqual(e.ar_ivalue, [43, 54, 32])
+        e.freeze()
+        self.assertEqual(e.ar_ivalue, (43, 54, 32))
+        with self.assertRaises(AttributeError):
+            e.ar_ivalue.append(12)
+        self.assertEqual(e.ar_ivalue, (43, 54, 32))
+
+    def test_mutable_object_and_class_freeze_container(self):
+
+        class E(dm.Element, options=(dm.ObjectMutable, dm.ClassMutable)):
+            ar_ivalue: list[int] = [43, 54]
+
+        self.assertEqual(E.ar_ivalue, [43, 54])
+        E.ar_ivalue.append(13)
+        self.assertEqual(E.ar_ivalue, [43, 54, 13])
+        e = E()
+        self.assertEqual(e.ar_ivalue, [43, 54, 13])
+        e.ar_ivalue.append(14)
+        self.assertEqual(e.ar_ivalue, [43, 54, 13, 14])
+        e.freeze()
+        self.assertEqual(e.ar_ivalue, (43, 54, 13, 14))
+        with self.assertRaises(AttributeError):
+            e.ar_ivalue.append(15)
+        self.assertEqual(e.ar_ivalue, (43, 54, 13, 14))
+
+    def test_mutable_class_freeze_inheritance(self):
+
+        class E(dm.Element, options=(dm.ClassMutable)):
+            ivalue: int = 12
+
+        class E2(E):
+            pass
+
+        self.assertEqual(E2.ivalue, 12)
+        with self.assertRaises(dm.ReadOnlyField):
+            E2.ivalue = 13
+        self.assertEqual(E2.ivalue, 12)
+        e = E2()
+        self.assertEqual(e.ivalue, 12)
+        with self.assertRaises(dm.ReadOnlyField):
+            e.ivalue = 14
+        self.assertEqual(e.ivalue, 12)
+
+    def test_mutable_object_freeze_inheritance(self):
+
+        class E(dm.Element, options=(dm.ObjectMutable)):
+            ivalue: int = 12
+
+        class E2(E):
+            pass
+
+        self.assertEqual(E2.ivalue, 12)
+        with self.assertRaises(dm.ReadOnlyField):
+            E2.ivalue = 13
+        self.assertEqual(E2.ivalue, 12)
+        e = E2()
+        self.assertEqual(e.ivalue, 12)
+        with self.assertRaises(dm.ReadOnlyField):
+            e.ivalue = 14
+        self.assertEqual(e.ivalue, 12)
+
+    def test_mutable_object_and_class_freeze_inheritance(self):
+
+        class E(dm.Element, options=(dm.ObjectMutable, dm.ClassMutable)):
+            ivalue: int = 12
+
+        class E2(E):
+            pass
+
+        self.assertEqual(E2.ivalue, 12)
+        with self.assertRaises(dm.ReadOnlyField):
+            E2.ivalue = 13
+        self.assertEqual(E2.ivalue, 12)
+        e = E2()
+        self.assertEqual(e.ivalue, 12)
+        with self.assertRaises(dm.ReadOnlyField):
+            e.ivalue = 14
+        self.assertEqual(e.ivalue, 12)
+
+    def test_mutable_object_and_class_freeze_inheritance_noleak(self):
+
+        class E(dm.Element, options=(dm.ObjectMutable, dm.ClassMutable)):
+            ivalue: int = 12
+
+        class E2(E):
+            pass
+
+        self.assertEqual(E2.ivalue, 12)
+        with self.assertRaises(dm.ReadOnlyField):
+            E2.ivalue = 13
+        self.assertEqual(E2.ivalue, 12)
+        e2 = E2()
+        self.assertEqual(e2.ivalue, 12)
+        with self.assertRaises(dm.ReadOnlyField):
+            e2.ivalue = 14
+        self.assertEqual(e2.ivalue, 12)
+
+        # no Leak
+
+        self.assertEqual(E.ivalue, 12)
+        E.ivalue = 13
+        self.assertEqual(E.ivalue, 13)
+        e = E()
+        self.assertEqual(e.ivalue, 13)
+        e.ivalue = 14
+        self.assertEqual(e.ivalue, 14)
+        e.freeze()
+        self.assertEqual(e.ivalue, 14)
+        with self.assertRaises(dm.ReadOnlyField):
+            e.ivalue = 15
+        self.assertEqual(e.ivalue, 14)
+
+        # no Leak 2
+
+        self.assertEqual(E2.ivalue, 12)
+        with self.assertRaises(dm.ReadOnlyField):
+            E2.ivalue = 13
+        self.assertEqual(E2.ivalue, 12)
+        e2 = E2()
+        self.assertEqual(e2.ivalue, 12)
+        with self.assertRaises(dm.ReadOnlyField):
+            e2.ivalue = 14
+        self.assertEqual(e2.ivalue, 12)
+
+    def test_mutable_class_freeze_nested_element(self):
+
+        class NElem(dm.Element):
+            ivalue: int = 43
+
+        class E(dm.Element, options=(dm.ClassMutable)):
+            e: NElem = NElem()
+
+        E.e.ivalue = 12
+        self.assertEqual(E.e.ivalue, 12)
+        E.freeze_class()
+        self.assertEqual(E.e.ivalue, 12)
+        with self.assertRaises(dm.ReadOnlyField):
+            E.e.ivalue = 13
+        self.assertEqual(E.e.ivalue, 12)
+        e = E()
+        self.assertEqual(e.e.ivalue, 12)
+        with self.assertRaises(dm.ReadOnlyField):
+            e.e.ivalue = 14
+        self.assertEqual(e.e.ivalue, 12)
+
+    def test_mutable_object_freeze_nested_element(self):
+        class NElem(dm.Element):
+            ivalue: int = 43
+
+        class E(dm.Element, options=(dm.ObjectMutable)):
+            e: NElem = NElem()
+
+        self.assertEqual(E.e.ivalue, 43)
+        with self.assertRaises(dm.ReadOnlyField):
+            E.e.ivalue = 13
+        self.assertEqual(E.e.ivalue, 43)
+        e = E()
+        self.assertEqual(e.e.ivalue, 43)
+        e.e.ivalue = 14
+        self.assertEqual(e.e.ivalue, 14)
+        e.freeze()
+        self.assertEqual(e.e.ivalue, 14)
+        with self.assertRaises(dm.ReadOnlyField):
+            e.e.ivalue = 15
+        self.assertEqual(e.e.ivalue, 14)
+
+    def test_mutable_object_and_class_freeze_nested_element(self):
+        class NElem(dm.Element):
+            ivalue: int = 43
+
+        class E(dm.Element, options=(dm.ObjectMutable, dm.ClassMutable)):
+            e: NElem = NElem()
+
+        self.assertEqual(E.e.ivalue, 43)
+        E.e.ivalue = 13
+        self.assertEqual(E.e.ivalue, 13)
+        e = E()
+        self.assertEqual(e.e.ivalue, 13)
+        e.e.ivalue = 14
+        self.assertEqual(e.e.ivalue, 14)
+        e.e.freeze()
+        self.assertEqual(e.e.ivalue, 14)
+        with self.assertRaises(dm.ReadOnlyField):
+            e.e.ivalue = 15
+        self.assertEqual(e.e.ivalue, 14)
+
+    def test_element_clone(self):
+        class Elem(dm.Element):
+            ivalue: int = 43
+
+        self.assertTrue(Elem.frozen_cls)
+        self.assertFalse(Elem.mutable_obj)
+
+        e = Elem()
+        print(e)
+
+        new_obj1 = e.clone_as_mutable_variant()
+        self.assertFalse(new_obj1.frozen_cls)
+        self.assertTrue(new_obj1.mutable_obj)
+        self.assertIsInstance(new_obj1, Elem)
+        self.assertEqual(new_obj1.ivalue, 43)
+        new_obj1.ivalue = 55
+        self.assertEqual(new_obj1.ivalue, 55)
+
+        new_obj2 = e.clone_as_mutable_variant()
+        self.assertFalse(new_obj2.frozen_cls)
+        self.assertTrue(new_obj2.mutable_obj)
+        self.assertNotEqual(new_obj1, new_obj2)
+        self.assertEqual(type(new_obj1), type(new_obj2))
+        self.assertEqual(new_obj2.ivalue, 43)
+        new_obj2.ivalue = 56
+        self.assertEqual(new_obj2.ivalue, 56)
+
+        new_obj3 = e.clone_as_mutable_variant()
+        self.assertFalse(new_obj3.frozen_cls)
+        self.assertTrue(new_obj3.mutable_obj)
+        self.assertNotEqual(new_obj1, new_obj3)
+        self.assertNotEqual(new_obj2, new_obj3)
+        self.assertEqual(type(new_obj1), type(new_obj3))
+        self.assertEqual(type(new_obj2), type(new_obj3))
+        self.assertEqual(new_obj3.ivalue, 43)
+        new_obj3.ivalue = 57
+        self.assertEqual(new_obj3.ivalue, 57)
+
+        self.assertEqual(e.ivalue, 43)
+        with self.assertRaises(dm.ReadOnlyField):
+            e.ivalue = 15
+        self.assertEqual(e.ivalue, 43)
+
+        self.assertEqual(new_obj1.ivalue, 55)
+        new_obj1.freeze()
+        self.assertEqual(new_obj1.ivalue, 55)
+        with self.assertRaises(dm.ReadOnlyField):
+            new_obj1.ivalue = 15
+        self.assertEqual(new_obj1.ivalue, 55)
+
+        self.assertEqual(new_obj2.ivalue, 56)
+        self.assertEqual(new_obj3.ivalue, 57)
+        new_obj2.ivalue = 76
+        self.assertEqual(new_obj2.ivalue, 76)
+        self.assertEqual(new_obj3.ivalue, 57)
+        self.assertEqual(new_obj1.ivalue, 55)
+        new_obj2.freeze()
+        self.assertEqual(new_obj2.ivalue, 76)
+        with self.assertRaises(dm.ReadOnlyField):
+            new_obj2.ivalue = 15
+        self.assertEqual(new_obj2.ivalue, 76)
+
+        self.assertTrue(e.frozen)
+        self.assertTrue(new_obj1.frozen)
+        self.assertTrue(new_obj2.frozen)
+        self.assertFalse(new_obj3.frozen)
+
+    def test_element_clone_inheritance(self):
+        class ElemA(dm.Element):
+            ivalue: int = 43
+
+        class ElemB(ElemA):
+            ivalue = 18
+
+        elemA = ElemA()
+        elemB = ElemB()
+
+        _elemA = elemA.clone_as_mutable_variant()
+        _elemB = elemB.clone_as_mutable_variant()
+
+        self.assertIsInstance(elemB, type(elemA))
+        self.assertIsInstance(_elemA, type(elemA))
+        self.assertIsInstance(_elemB, type(elemB))
+        self.assertIsInstance(_elemB, type(_elemA))
+
+    def test_element_clone_inheritance_nested(self):
+        class ElemAInner(dm.Element):
+            fvalue: float = 0.123
+
+        class ElemA(dm.Element):
+            ivalue: int = 43
+            el1: ElemAInner = ElemAInner()
+
+        class ElemBInner(ElemAInner):
+            fvalue = 0.9
+
+        class ElemB(ElemA):
+            ivalue = 18
+            el1 = ElemAInner(fvalue=6.54)
+            el2: ElemBInner = ElemBInner()
+
+        self.assertIsInstance(ElemA.el1, ElemAInner)
+        self.assertIsInstance(ElemB.el1, ElemAInner)
+        self.assertIsInstance(ElemB.el2, ElemAInner)
+        self.assertIsInstance(ElemB.el2, ElemBInner)
+        self.assertNotIsInstance(ElemB.el1, ElemBInner)
+
+        elemA = ElemA()
+        elemB = ElemB()
+
+        _elemA = elemA.clone_as_mutable_variant()
+        _elemB = elemB.clone_as_mutable_variant()
+
+        self.assertIsInstance(elemB, type(elemA))
+        self.assertIsInstance(_elemA, type(elemA))
+        self.assertIsInstance(_elemB, type(elemB))
+        self.assertIsInstance(_elemB, type(_elemA))
+
+        self.assertIsInstance(_elemB.el1, type(_elemA.el1))
+        self.assertIsInstance(_elemA.el1, type(elemA.el1))
+        self.assertIsInstance(_elemB.el1, type(elemB.el1))
+        self.assertIsInstance(_elemB.el1, type(_elemA.el1))
+
+        self.assertIsInstance(_elemB.el2, type(_elemA.el1))
+        self.assertIsInstance(_elemB.el2, type(elemB.el1))
+        self.assertIsInstance(_elemB.el2, type(_elemA.el1))
 
 
 # ---------- main ----------

test/test_feature.py

@@ -61,7 +61,7 @@ class FeatureTest(unittest.TestCase):
         app1 = Appliance1()
 
         self.assertIsInstance(Appliance1.__lam_schema__["VarStrOuter"], dm.LAMField)
-        self.assertIsInstance(app1.__lam_schema__["VarStrOuter"], dm.FrozenLAMField)
+        self.assertTrue(app1.__lam_schema__["VarStrOuter"].is_frozen())
         self.assertIn("Feature1", app1.__lam_schema__["features"])
         self.assertIn("VarStrInner", app1.__lam_schema__["features"]["Feature1"].__lam_schema__)
         self.assertIsInstance(
@@ -69,7 +69,8 @@ class FeatureTest(unittest.TestCase):
             dm.LAMField,
         )
         self.assertTrue(hasattr(app1, "Feature1"))
-        self.assertIsInstance(app1.Feature1.__lam_schema__["VarStrInner"], dm.FrozenLAMField)
+        self.assertTrue(app1.Feature1.frozen)
+        self.assertTrue(app1.Feature1.__lam_schema__["VarStrInner"].is_frozen())
         self.assertTrue(hasattr(app1.Feature1, "VarStrInner"))
 
     def test_inheritance(self):
@@ -109,7 +110,7 @@ class FeatureTest(unittest.TestCase):
         app3 = Appliance3()
 
         self.assertIsInstance(Appliance1.__lam_schema__["VarStrOuter"], dm.LAMField)
-        self.assertIsInstance(app1.__lam_schema__["VarStrOuter"], dm.FrozenLAMField)
+        self.assertTrue(app1.__lam_schema__["VarStrOuter"].is_frozen())
         self.assertIn("Feature1", app1.__lam_schema__["features"])
         self.assertIn("VarStrInner", app1.__lam_schema__["features"]["Feature1"].__lam_schema__)
         self.assertIsInstance(
@@ -117,7 +118,7 @@ class FeatureTest(unittest.TestCase):
             dm.LAMField,
         )
         self.assertTrue(hasattr(app1, "Feature1"))
-        self.assertIsInstance(app1.Feature1.__lam_schema__["VarStrInner"], dm.FrozenLAMField)
+        self.assertTrue(app1.Feature1.__lam_schema__["VarStrInner"].is_frozen())
         self.assertTrue(hasattr(app1.Feature1, "VarStrInner"))
         self.assertEqual(app1.VarStrOuter, "testvalue APPLIANCE1")
         self.assertEqual(app1.Feature1.VarStrInner, "testvalue FEATURE1")
@@ -129,6 +130,12 @@ class FeatureTest(unittest.TestCase):
         self.assertEqual(app3.Feature1.VarInt, 42)
         self.assertEqual(app3.Feature3.VarStrInner, "testvalue FEATURE3")
 
+        class Appliance4(Appliance3):
+            VarStrOuter = "testvalue APPLIANCE4"
+
+            class Feature1(Appliance3.Feature1):
+                VarStrInner = "testvalue FEATURE1 modded 3"
+
     def test_inheritance2(self):
         """Testing first appliance feature, and Field types (simple)"""
 
@@ -178,14 +185,6 @@ class FeatureTest(unittest.TestCase):
         self.assertEqual(app3.Feature1.VarStrInner, "testvalue FEATURE1")
         self.assertEqual(app4.Feature1.VarStrInner, "testvalue FEATURE4")
 
-    def test_new_field_forbidden(self):
-        class App(dm.Appliance):
-            x: int = 1
-
-        app = App()
-        with self.assertRaises(dm.NewFieldForbidden):
-            app.y = 2
-
     def test_inherit_declared(self):
         class App(dm.Appliance):
             class F1(dm.Feature):
@@ -646,6 +645,22 @@ class FeatureTest(unittest.TestCase):
                 class F1(dm.Feature):
                     fail: str = "oops"
 
+    def test_initializer(self):
+        class App(dm.Appliance):
+            integ: int = 18
+
+            class F(dm.Feature):
+                nums: list[int] = [1, 2]
+                tag: str = "x"
+
+            @classmethod
+            def __initializer(cls):
+                cls.F.tag = "test"
+                cls.F.nums.append(3)
+
+        self.assertEqual(App.F.tag, "test")
+        self.assertEqual(App.F.nums, (1, 2, 3))
+
 
 # ---------- main ----------