partially fix features

pyproject.toml

@@ -7,7 +7,7 @@
 # work.  If not, see <https://creativecommons.org/licenses/by-nc-sa/4.0/>.
 
 [build-system]
-requires = ["setuptools>=63", "wheel", "setuptools_scm","frozendict","typeguard"]
+requires = ["setuptools>=63", "wheel", "setuptools_scm"]
 build-backend = "setuptools.build_meta"
 
 [tool.setuptools_scm]
@@ -35,8 +35,8 @@ classifiers = [
 dependencies = [
     'importlib-metadata; python_version<"3.9"',
     'packaging',
-    'pydantic',
-    'runtype'
+    'frozendict',
+    'typeguard'
 ]
 dynamic = ["version"]
 

src/dabmodel/__init__.py

@@ -13,6 +13,7 @@ Main module __init__ file.
 from .__metadata__ import __version__, __Summuary__, __Name__
 from .model import (
     DABFieldInfo,
+    DABField,
     BaseAppliance,
     BaseFeature,
     DABModelException,
@@ -27,4 +28,6 @@ from .model import (
     IncompletelyAnnotatedField,
     ImportForbidden,
     FunctionForbidden,
+    FrozenDABField,
+    InvalidFeatureInheritance,
 )

src/dabmodel/model.py

@@ -1,11 +1,35 @@
-from typing import Optional, TypeVar, Generic, Union, get_origin, get_args, List, Dict, Any, Tuple, Set, Annotated, FrozenSet
+""" dabmodel model module
+This module implements DAB model classes.
+This module contains metaclass and bases classes used to create models.
+BaseAppliance can be used to create a new Appliance Data.
+BaseFeature can be used to create new Appliance's Features."""
+
+from typing import (
+    Optional,
+    TypeVar,
+    Generic,
+    Union,
+    get_origin,
+    get_args,
+    List,
+    Dict,
+    Any,
+    Tuple,
+    Set,
+    Annotated,
+    FrozenSet,
+    Callable,
+    Type,
+)
 from types import UnionType, FunctionType, SimpleNamespace
-from frozendict import deepfreeze
 from copy import deepcopy, copy
-from pprint import pprint
-from typeguard import check_type, TypeCheckError, CollectionCheckStrategy
+
+# from pprint import pprint
 import math
 
+from frozendict import deepfreeze
+from typeguard import check_type, TypeCheckError, CollectionCheckStrategy
+
 ALLOWED_ANNOTATIONS = {
     "Union": Union,
     "Optional": Optional,
@@ -31,52 +55,101 @@ ALLOWED_ANNOTATIONS = {
 }
 
 ALLOWED_MODEL_FIELDS_TYPES = (str, int, float, complex, bool, bytes)
-ALLOWED_MODEL_FIELDS_CONTAINERS = (dict, list, set, frozenset, tuple)
 
 
-TV_ALLOWED_MODEL_FIELDS_TYPES = TypeVar("TV_ALLOWED_MODEL_FIELDS_TYPES", *ALLOWED_MODEL_FIELDS_TYPES, *ALLOWED_MODEL_FIELDS_CONTAINERS)
+# TV_ALLOWED_MODEL_FIELDS_TYPES = TypeVar("TV_ALLOWED_MODEL_FIELDS_TYPES", *ALLOWED_MODEL_FIELDS_TYPES, *ALLOWED_MODEL_FIELDS_CONTAINERS)
 
 
-class DABModelException(Exception): ...
+class DABModelException(Exception):
+    """DABModelException Exception class
+    Base Exception for DABModelException class
+    """
+
+class ReservedFieldName(Exception):
+    """DABModelException Exception class
+    Base Exception for DABModelException class
+    """
+    
+class MultipleInheritanceForbidden(DABModelException):
+    """MultipleInheritanceForbidden Exception class
+    Multiple inheritance is forbidden when using dabmodel
+    """
 
 
-class MultipleInheritanceForbidden(DABModelException): ...
+class BrokenInheritance(DABModelException):
+    """BrokenInheritance Exception class
+    inheritance chain is broken
+    """
 
 
-class BrokenInheritance(DABModelException): ...
+class ReadOnlyField(DABModelException):
+    """ReadOnlyField Exception class
+    The used Field is ReadOnly
+    """
 
 
-class ReadOnlyField(DABModelException): ...
+class NewFieldForbidden(DABModelException):
+    """NewFieldForbidden Exception class
+    Field creation is forbidden
+    """
 
 
-class NewFieldForbidden(DABModelException): ...
+class InvalidFieldAnnotation(DABModelException):
+    """InvalidFieldAnnotation Exception class
+    The field annotation is invalid
+    """
 
 
-class InvalidFieldAnnotation(DABModelException): ...
+class InvalidInitializerType(DABModelException):
+    """InvalidInitializerType Exception class
+    The initializer is not a valid type
+    """
 
 
-class InvalidInitializerType(DABModelException): ...
+class NotAnnotatedField(InvalidFieldAnnotation):
+    """NotAnnotatedField Exception class
+    The Field is not Annotated
+    """
 
 
-class NotAnnotatedField(InvalidFieldAnnotation): ...
+class IncompletelyAnnotatedField(InvalidFieldAnnotation):
+    """IncompletelyAnnotatedField Exception class
+    The field annotation is incomplete
+    """
 
 
-class IncompletelyAnnotatedField(InvalidFieldAnnotation): ...
+class ReadOnlyFieldAnnotation(DABModelException):
+    """ReadOnlyFieldAnnotation Exception class
+    Field annotation connot be modified
+    """
 
 
-class ReadOnlyFieldAnnotation(DABModelException): ...
+class InvalidFieldValue(DABModelException):
+    """InvalidFieldValue Exception class
+    The Field value is invalid
+    """
 
 
-class InvalidFieldValue(DABModelException): ...
+class NonExistingField(DABModelException):
+    """NonExistingField Exception class
+    The given Field is non existing
+    """
 
 
-class NonExistingField(DABModelException): ...
+class ImportForbidden(DABModelException):
+    """ImportForbidden Exception class
+    Imports are forbidden
+    """
 
+class InvalidFeatureInheritance(DABModelException):
+    """InvalidFeatureInheritance Exception class
+    Features of same name in child appliance need to be from same type
+    """
 
-class ImportForbidden(DABModelException): ...
-
-
-class FunctionForbidden(DABModelException): ...
+class FunctionForbidden(DABModelException):
+    """FunctionForbidden Exception class
+    function call are forbidden
+    """
 
 
 ALLOWED_HELPERS_MATH = SimpleNamespace(
@@ -134,7 +207,7 @@ def _blocked_import(*args, **kwargs):
 def _resolve_annotation(ann):
     if isinstance(ann, str):
         # Safe eval against a **whitelist** only
-        return eval(ann, {"__builtins__": {}}, ALLOWED_ANNOTATIONS)
+        return eval(ann, {"__builtins__": {}}, ALLOWED_ANNOTATIONS)  # pylint: disable=eval-used
     return ann
 
 
@@ -152,15 +225,15 @@ def _peel_annotated(t: Any) -> Any:
             return t
 
 
-def _check_annotation_definition(_type) -> bool:
+def _check_annotation_definition(_type) -> bool:  # pylint: disable=too-complex,too-many-return-statements
     _type = _peel_annotated(_type)
     # handle Optional[] and Union[None,...]
     if (get_origin(_type) is Union or get_origin(_type) is UnionType) and type(None) in get_args(_type):
-        return all([_check_annotation_definition(_) for _ in get_args(_type) if _ is not type(None)])
+        return all(_check_annotation_definition(_) for _ in get_args(_type) if _ is not type(None))
 
     # handle other Union[...]
     if get_origin(_type) is Union or get_origin(_type) is UnionType:
-        return all([_check_annotation_definition(_) for _ in get_args(_type)])
+        return all(_check_annotation_definition(_) for _ in get_args(_type))
 
     # handle Dict[...]
     if get_origin(_type) is dict:
@@ -176,147 +249,200 @@ def _check_annotation_definition(_type) -> bool:
             raise IncompletelyAnnotatedField(f"Annotation requires inner definition: {_type}")
         if len(inner_types) == 2 and inner_types[1] is Ellipsis:
             return _check_annotation_definition(inner_types[0])
-        return all([_check_annotation_definition(_) for _ in inner_types])
+        return all(_check_annotation_definition(_) for _ in inner_types)
 
     # handle Set[],Tuple[],FrozenSet[],List[]
     if get_origin(_type) in [set, frozenset, tuple, list]:
         inner_types = get_args(_type)
         if len(inner_types) == 0:
             raise IncompletelyAnnotatedField(f"Annotation requires inner definition: {_type}")
-        return all([_check_annotation_definition(_) for _ in inner_types])
+        return all(_check_annotation_definition(_) for _ in inner_types)
 
     if _type in ALLOWED_MODEL_FIELDS_TYPES:
         return True
     return False
 
 
-class BaseConstraint(Generic[TV_ALLOWED_MODEL_FIELDS_TYPES]):
+T_Field = TypeVar("T_Field")
+
+
+class BaseConstraint(Generic[T_Field]):
+    """BaseConstraint class
+    Base class for Field's constraints
+    """
+
     _bound_type: type
 
     def __init__(self): ...
 
-    def check(self, value: TV_ALLOWED_MODEL_FIELDS_TYPES) -> bool: ...
+    def check(self, value: T_Field) -> bool:
+        """Check if a Constraint is completed"""
+        return True
 
 
 def _deepfreeze(value):
+    """recursive freeze helper function"""
     if isinstance(value, dict):
         return deepfreeze(value)
-    elif isinstance(value, set):
+    if isinstance(value, set):
         return frozenset(_deepfreeze(v) for v in value)
-    elif isinstance(value, list):
+    if isinstance(value, list):
         return tuple(_deepfreeze(v) for v in value)
-    elif isinstance(value, tuple):
+    if isinstance(value, tuple):
         return tuple(_deepfreeze(v) for v in value)
     return value
 
 
 class DABFieldInfo:
-    def __init__(self, *, doc: str = "", constraints: list[BaseConstraint] = []):
+    """This Class allows to describe a Field in Appliance class"""
+
+    def __init__(self, *, doc: str = "", constraints: Optional[list[BaseConstraint]] = None):
         self._doc: str = doc
-        self._constraints: list[BaseConstraint] = constraints
+        self._constraints: list[BaseConstraint]
+        if constraints is None:
+            self._constraints = []
+        else:
+            self._constraints = constraints
 
     @property
-    def doc(self):
+    def doc(self) -> str:
+        """Returns Field's documentation"""
         return self._doc
 
     @property
-    def constraints(self):
+    def constraints(self) -> list[BaseConstraint[Any]]:
+        """Returns Field's constraints"""
         return self._constraints
 
 
-class DABField(Generic[TV_ALLOWED_MODEL_FIELDS_TYPES]):
-    def __init__(self, name: str, v: Optional[TV_ALLOWED_MODEL_FIELDS_TYPES], a: Any, i: str):
+class DABField(Generic[T_Field]):
+    """This class describe a Field in Schema"""
+
+    def __init__(self, name: str, v: Optional[T_Field], a: Any, i: DABFieldInfo):
         self._name: str = name
         self._source: Optional[type] = None
-        self._default_value: Optional[TV_ALLOWED_MODEL_FIELDS_TYPES] = v
-        self._value: Optional[TV_ALLOWED_MODEL_FIELDS_TYPES] = v
+        self._default_value: Optional[T_Field] = v
+        self._value: Optional[T_Field] = v
         self._annotations: Any = a
         self._info: DABFieldInfo = i
-        self._constraints: List[BaseConstraint] = i.constraints
+        self._constraints: List[BaseConstraint[Any]] = i.constraints
 
     def add_source(self, s: type) -> None:
+        """Adds source Appliance to the Field"""
         self._source = s
 
     @property
-    def doc(self):
+    def doc(self) -> str:
+        """Returns Field's documentation"""
         return self._info.doc
 
     def add_constraint(self, c: BaseConstraint) -> None:
+        """Adds constraint to the Field"""
         self._constraints.append(c)
 
     @property
     def constraints(self) -> list[BaseConstraint]:
+        """Returns Field's constraint"""
         return self._info.constraints
 
     @property
-    def default_value(self):
+    def default_value(self) -> Any:
+        """Returns Field's default value (frozen)"""
         return _deepfreeze(self._default_value)
 
-    def update_value(self, v: Optional[TV_ALLOWED_MODEL_FIELDS_TYPES] = None) -> None:
+    def update_value(self, v: Optional[T_Field] = None) -> None:
+        """Updates Field's value"""
         self._value = v
 
     @property
-    def value(self):
+    def value(self) -> Any:
+        """Returns Field's value (frosen)"""
         return _deepfreeze(self._value)
 
     @property
-    def raw_value(self):
+    def raw_value(self) -> Optional[T_Field]:
+        """Returns Field's value"""
         return self._value
 
     @property
     def annotations(self) -> Any:
+        """Returns Field's annotation"""
         return self._annotations
 
 
-class FrozenDABField(Generic[TV_ALLOWED_MODEL_FIELDS_TYPES]):
+class FrozenDABField(Generic[T_Field]):
+    """FrozenDABField class
+    a read-only proxy of a Field
+    """
+
     def __init__(self, inner_field: DABField):
         self._inner_field = inner_field
 
     @property
-    def doc(self):
-        return self._inner_field.doc
+    def doc(self) -> str:
+        """Returns Field's documentation (frozen)"""
+        return _deepfreeze(self._inner_field.doc)
 
     @property
-    def constraints(self):
+    def constraints(self) -> tuple[BaseConstraint]:
+        """Returns Field's constraint (frozen)"""
         return _deepfreeze(self._inner_field.constraints)
 
     @property
-    def default_value(self):
+    def default_value(self) -> Any:
+        """Returns Field's default value (frozen)"""
         return self._inner_field.default_value
 
     @property
-    def value(self):
+    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 _deepfreeze(self._inner_field.annotations)
 
 
 class ModelSpecView:
+    """ModelSpecView class
+    A class that will act as fake BaseElement proxy to allow setting values"""
+
     __slots__ = ("_vals", "_types", "_touched", "_name", "_module")
 
-    def __init__(self, values: dict, types_map: dict[str, type], name, module):
+    def __init__(self, values: dict[str, Any], types_map: dict[str, type], name: str, module: str):
+        self._name: str
+        self._vals: dict[str, Any]
+        self._types: dict[str, type]
+        self._touched: set
+        self._module: str
         object.__setattr__(self, "_vals", dict(values))
         object.__setattr__(self, "_types", types_map)
-        object.__setattr__(self, "_touched", set())
         object.__setattr__(self, "_name", name)
         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
 
-    def __getattr__(self, name):
+    @__module__.setter
+    def __module__(self, value: str):
+        pass
+
+    def __getattr__(self, name: str) -> Any:
+        """internal proxy getattr"""
         if name not in self._types:
             raise AttributeError(f"Unknown field {name}")
         return self._vals[name]
 
-    def __setattr__(self, name, value):
+    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]
@@ -331,23 +457,35 @@ class ModelSpecView:
             raise InvalidFieldValue(f"Field <{name}> value is not of expected type {T}.") from exp
 
         self._vals[name] = value
-        self._touched.add(name)
 
     def export(self) -> dict:
+        """exports all proxified values"""
         return dict(self._vals)
 
-    def diff(self) -> dict:
-        return {k: self._vals[k] for k in self._touched}
+
+T_Meta = TypeVar("T_Meta", bound="BaseMeta")
+T_BE = TypeVar("T_BE", bound="BaseElement")
 
 
 class BaseMeta(type):
-    def __new__(mcls, name, bases, namespace):
-        # print("__NEW__ Defining:", name, "with keys:", list(namespace))
+    """metaclass to use to build BaseElement"""
+
+    modified_field: Dict[str, Any] = {}
+    new_fields: Dict[str, DABField[Any]] = {}
+    initializer: Optional[Callable[..., Any]] = None
+    __DABSchema__: dict[str, Any] = {}
+
+    @classmethod
+    def pre_check(
+        mcs: type["BaseMeta"], name: str, bases: tuple[type[Any], ...], namespace: dict[str, Any]  # pylint: disable=unused-argument
+    ) -> None:
+        """early BaseElement checks"""
+        print("__NEW__ Defining:", name, "with keys:", list(namespace))
 
         if len(bases) > 1:
             raise MultipleInheritanceForbidden("Multiple inheritance is not supported by dabmodel")
-        elif len(bases) == 0:  # base class (BaseElement)
-            namespace["__DABSchema__"] = dict()
+        if len(bases) == 0:  # base class (BaseElement)
+            namespace["__DABSchema__"] = {}
         else:  # standard inheritance
             # check class tree origin
             if "__DABSchema__" not in dir(bases[0]):
@@ -360,16 +498,19 @@ class BaseMeta(type):
             for _funknown in [_ for _ in namespace["__annotations__"] if _ not in namespace.keys()]:
                 namespace[_funknown] = None
 
+    @classmethod
+    def pre_processing(mcs: type["BaseMeta"], name: str, bases: tuple[type[Any], ...], namespace: dict[str, Any]):
+        """preprocessing BaseElement"""
         # iterating new and modified fields
-        modified_field: Dict[str, Any] = {}
-        new_fields: Dict[str, DABField] = {}
-        initializer: Optional[type] = None
+        mcs.modified_field = {}
+        mcs.new_fields = {}
+        mcs.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 = _fvalue.__func__
+                mcs.initializer = _fvalue.__func__
                 if name.startswith("_"):
                     initializer_name = "__initializer"
                 else:
@@ -378,117 +519,102 @@ class BaseMeta(type):
                 pass
             else:
                 # print(f"Parsing Field: {_fname} / {_fvalue}")
-                # Modified fields
-                if len(bases) == 1 and _fname in namespace["__DABSchema__"].keys():
-                    # print(f"Modified field: {_fname}")
-                    if "__annotations__" in namespace and _fname in namespace["__annotations__"]:
-                        raise ReadOnlyFieldAnnotation("annotations cannot be modified on derived classes")
-                    try:
-                        check_type(
-                            _fvalue,
-                            namespace["__DABSchema__"][_fname].annotations,
-                            collection_check_strategy=CollectionCheckStrategy.ALL_ITEMS,
-                        )
-                    except TypeCheckError as exp:
-                        raise InvalidFieldValue(
-                            f"Field <{_fname}> New Field value is not of expected type {bases[0].__annotations__[_fname]}."
-                        ) from exp
-                    modified_field[_fname] = _fvalue
-                # New fieds
-                else:
-                    # print(f"New field: {_fname}")
-                    # print(f"type is: {type(_fvalue)}")
-                    # print(f"value is: {_fvalue}")
-
-                    # check if field is annotated
-                    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
-                    if isinstance(namespace["__annotations__"][_fname], str):
-                        namespace["__annotations__"][_fname] = _resolve_annotation(namespace["__annotations__"][_fname])
-
-                    if not _check_annotation_definition(namespace["__annotations__"][_fname]):
-                        raise InvalidFieldAnnotation(f"Field <{_fname}> has not an allowed or valid annotation.")
-
-                    _finfo: Optional[DABFieldInfo] = DABFieldInfo()
-                    origin = get_origin(namespace["__annotations__"][_fname])
-                    tname = getattr(origin, "__name__", "") or getattr(origin, "__qualname__", "") or str(origin)
-                    if "Annotated" in tname:
-                        args = get_args(namespace["__annotations__"][_fname])
-                        if args:
-                            if len(args) > 2:
-                                raise InvalidFieldAnnotation(f"Field <{_fname}> had invalid Annotated value.")
-                            if len(args) == 2 and not isinstance(args[1], DABFieldInfo):
-                                raise InvalidFieldAnnotation(f"Only DABFieldInfo object is allowed as Annotated data.")
-
-                            _finfo = args[1]
-
-                    # print(f"annotation is: {namespace['__annotations__'][_fname]}")
-                    # check if value is valid
-                    try:
-                        check_type(
-                            _fvalue, namespace["__annotations__"][_fname], collection_check_strategy=CollectionCheckStrategy.ALL_ITEMS
-                        )
-                    except TypeCheckError as exp:
-                        raise InvalidFieldValue(
-                            f"Value of Field <{_fname}> is not of expected type {namespace['__annotations__'][_fname]}."
-                        ) from exp
-                    new_fields[_fname] = DABField(_fname, _fvalue, namespace["__annotations__"][_fname], _finfo)
-
+                if len(bases) == 1 and _fname in namespace["__DABSchema__"].keys():  # Modified fields
+                    mcs.pre_processing_modified_fields(name, bases, namespace, _fname, _fvalue)
+                else:  # New fieds
+                    mcs.pre_processing_new_fields(name, bases, namespace, _fname, _fvalue)
         # removing modified fields from class (will add them back later)
-        for _fname in new_fields.keys():
+        for _fname in mcs.new_fields:
             del namespace[_fname]
-        for _fname in modified_field.keys():
+        for _fname in mcs.modified_field:
             del namespace[_fname]
-        if initializer is not None:
+        if mcs.initializer is not None and initializer_name is not None:
             del namespace[initializer_name]
 
-        orig_setattr = namespace.get("__setattr__", object.__setattr__)
+    @classmethod
+    def pre_processing_modified_fields(
+        mcs: type["BaseMeta"], name: str, bases: tuple[type[Any], ...], namespace: dict[str, Any], _fname: str, _fvalue: Any
+    ):  # pylint: disable=unused-argument
+        """preprocessing BaseElement modified Fields"""
+        print(f"Modified field: {_fname}")
+        if "__annotations__" in namespace and _fname in namespace["__annotations__"]:
+            raise ReadOnlyFieldAnnotation(f"annotations cannot be modified on derived classes {_fname}")
+        try:
+            check_type(
+                _fvalue,
+                namespace["__DABSchema__"][_fname].annotations,
+                collection_check_strategy=CollectionCheckStrategy.ALL_ITEMS,
+            )
+        except TypeCheckError as exp:
+            raise InvalidFieldValue(
+                f"Field <{_fname}> New Field value is not of expected type {bases[0].__annotations__[_fname]}."
+            ) from exp
+        mcs.modified_field[_fname] = _fvalue
 
-        def guarded_setattr(self, key, value):
-            if key.startswith("_"):  # allow private and dunder attrs
-                return orig_setattr(self, key, value)
-            # block writes after init if key is readonly
-            if key in self.__DABSchema__.keys():
-                if hasattr(self, key):
-                    raise ReadOnlyField(f"{key} is read-only")
-            else:
-                raise NewFieldForbidden(f"creating new fields is not allowed")
+    @classmethod
+    def pre_processing_new_fields(
+        mcs: type["BaseMeta"], name: str, bases: tuple[type[Any], ...], namespace: dict[str, Any], _fname: str, _fvalue: Any
+    ):  # pylint: disable=unused-argument
+        """preprocessing BaseElement new Fields"""
+        print(f"New field: {_fname}")
+        # print(f"type is: {type(_fvalue)}")
+        # print(f"value is: {_fvalue}")
 
-            return orig_setattr(self, key, value)
+        # check if field is annotated
+        if "__annotations__" not in namespace or _fname not in namespace["__annotations__"]:
+            raise NotAnnotatedField(f"Every dabmodel Fields must be annotated ({_fname})")
 
-        namespace["__setattr__"] = guarded_setattr
+        # check if annotation is allowed
+        if isinstance(namespace["__annotations__"][_fname], str):
+            namespace["__annotations__"][_fname] = _resolve_annotation(namespace["__annotations__"][_fname])
 
-        cls = super().__new__(mcls, name, bases, namespace)
+        if not _check_annotation_definition(namespace["__annotations__"][_fname]):
+            raise InvalidFieldAnnotation(f"Field <{_fname}> has not an allowed or valid annotation.")
 
-        for _fname, _fvalue in modified_field.items():
-            cls.__DABSchema__[_fname] = deepcopy(bases[0].__DABSchema__[_fname])
-            cls.__DABSchema__[_fname].update_value(_fvalue)
+        _finfo: DABFieldInfo = DABFieldInfo()
+        origin = get_origin(namespace["__annotations__"][_fname])
+        tname = getattr(origin, "__name__", "") or getattr(origin, "__qualname__", "") or str(origin)
+        if "Annotated" in tname:
+            args = get_args(namespace["__annotations__"][_fname])
+            if args:
+                if len(args) > 2:
+                    raise InvalidFieldAnnotation(f"Field <{_fname}> had invalid Annotated value.")
+                if len(args) == 2 and not isinstance(args[1], DABFieldInfo):
+                    raise InvalidFieldAnnotation("Only DABFieldInfo object is allowed as Annotated data.")
 
-        for _fname, _fvalue in new_fields.items():
-            _fvalue.add_source(cls)
-            cls.__DABSchema__[_fname] = _fvalue
+                _finfo = args[1]
+                
+        # check if value is valid
+        try:
+            check_type(_fvalue, namespace["__annotations__"][_fname], collection_check_strategy=CollectionCheckStrategy.ALL_ITEMS)
+        except TypeCheckError as exp:
+            raise InvalidFieldValue(f"Value of Field <{_fname}> is not of expected type {namespace['__annotations__'][_fname]}.") from exp
+        mcs.new_fields[_fname] = DABField(_fname, _fvalue, namespace["__annotations__"][_fname], _finfo)
 
-        if initializer is not None:
-            init_fieldvalues = dict()
-            init_fieldtypes = dict()
+    @classmethod
+    def call_initializer(
+        mcs: type["BaseMeta"], cls, name: str, bases: tuple[type[Any], ...], namespace: dict[str, Any]  # pylint: disable=unused-argument
+    ):
+        """BaseElement initializer processing"""
+        if mcs.initializer is not None:
+            init_fieldvalues = {}
+            init_fieldtypes = {}
             for _fname, _fvalue in cls.__DABSchema__.items():
-                init_fieldvalues[_fname] = deepcopy(_fvalue.raw_value)
-                init_fieldtypes[_fname] = _fvalue.annotations
+                if isinstance(_fvalue,DABField):
+                    init_fieldvalues[_fname] = deepcopy(_fvalue.raw_value)
+                    init_fieldtypes[_fname] = _fvalue.annotations
             fakecls = ModelSpecView(init_fieldvalues, init_fieldtypes, cls.__name__, cls.__module__)
             safe_globals = {"__builtins__": {"__import__": _blocked_import}, **ALLOWED_HELPERS_DEFAULT}
-            if initializer.__code__.co_freevars:
+            if mcs.initializer.__code__.co_freevars:
                 raise FunctionForbidden("__initializer must not use closures")
             safe_initializer = FunctionType(
-                initializer.__code__,
+                mcs.initializer.__code__,
                 safe_globals,
-                name=initializer.__name__,
-                argdefs=initializer.__defaults__,
+                name=mcs.initializer.__name__,
+                argdefs=mcs.initializer.__defaults__,
                 closure=None,
             )
-            safe_initializer(fakecls)
-            print(fakecls.diff())
+            safe_initializer(fakecls)  # pylint: disable=not-callable
             for _fname, _fvalue in fakecls.export().items():
                 try:
                     check_type(_fvalue, cls.__DABSchema__[_fname].annotations, collection_check_strategy=CollectionCheckStrategy.ALL_ITEMS)
@@ -497,27 +623,150 @@ class BaseMeta(type):
                         f"Value of Field <{_fname}> is not of expected type {namespace['__annotations__'][_fname]}."
                     ) from exp
                 cls.__DABSchema__[_fname].update_value(_fvalue)
-        return cls
+                
+    def __new__(mcs: type["BaseMeta"], name: str, bases: tuple[type[Any], ...], namespace: dict[str, Any]) -> Type:
+        """BaseElement new class"""
+        mcs.pre_check(name, bases, namespace)
+        mcs.pre_processing(name, bases, namespace)
+               
+        _cls = super().__new__(mcs, name, bases, namespace)
 
-    def __call__(cls, *args, **kw):
+        mcs.save_values(_cls, name, bases, namespace)
+        mcs.call_initializer(_cls, name, bases, namespace)
+        _cls.install_guard()
+        
+        return _cls
+    
+    @classmethod
+    def save_values(
+        mcs: type["BaseMeta"], cls, name: str, bases: tuple[type[Any], ...], namespace: dict[str, Any]  # pylint: disable=unused-argument
+    ):
+        for _fname, _fvalue in mcs.modified_field.items():
+            cls.__DABSchema__[_fname] = deepcopy(bases[0].__DABSchema__[_fname])
+            cls.__DABSchema__[_fname].update_value(_fvalue)
+
+        for _fname, _fvalue in mcs.new_fields.items():
+            _fvalue.add_source(mcs)
+            cls.__DABSchema__[_fname] = _fvalue
+            
+    def __call__(cls: Type, *args: Any, **kw: Any):  # intentionally untyped
+        """BaseElement new instance"""
         obj = super().__call__(*args, **kw)
 
-        for _fname in cls.__DABSchema__.keys():
-            setattr(obj, _fname, cls.__DABSchema__[_fname].value)
-        inst_schema = dict()
         for _fname, _fvalue in cls.__DABSchema__.items():
-            inst_schema[_fname] = FrozenDABField(_fvalue)
-        setattr(obj, "__DABSchema__", inst_schema)
-        return obj
+            if isinstance(_fvalue,DABField):
+                object.__setattr__(obj, _fname, _fvalue.value)
 
+        inst_schema = copy(obj.__DABSchema__)
+        for _fname, _fvalue in cls.__DABSchema__.items():
+            if isinstance(_fvalue,DABField):
+                inst_schema[_fname] = FrozenDABField(_fvalue)
+                
+        object.__setattr__(obj, "__DABSchema__", inst_schema)
+        cls.modify_object(obj)
+        
+        
+        return obj
+    
+    def modify_object(cls:Type,obj):
+        pass
+    
+    
+    def install_guard(cls:Type):
+        orig_setattr = getattr(cls,"__setattr__")
+        
+        # cls.orig_setattr = orig_setattr
+        
+        def guarded_setattr(_self, key: str, value: Any):
+            if key.startswith("_"):  # allow private and dunder attrs
+                return orig_setattr(_self, key, value)
+            # block writes after init if key is readonly
+            if key in _self.__DABSchema__.keys():
+                if key in _self.__dict__:
+                    raise ReadOnlyField(f"{key} is read-only")
+            elif key in _self.__DABSchema__["features"].keys():
+                if key in _self.__dict__:
+                    raise ReadOnlyField(f"{key} is read-only")
+            else:
+                raise NewFieldForbidden("creating new fields is not allowed")
+
+            return orig_setattr(_self, key, value)
+
+        setattr(cls, "__setattr__", guarded_setattr)
 
 class BaseElement(metaclass=BaseMeta):
+    """BaseElement class
+    Base class to apply metaclass and set common Fields.
+    """
+
+class BaseMetaFeature(BaseMeta):
     pass
 
+class BaseFeature(BaseElement,metaclass=BaseMetaFeature):
+    """BaseFeature class
+    Base class for Appliance's Features.
+    Features are optional traits of an appliance.
+    """
+    Enabled:bool=False
 
-class BaseFeature(BaseElement):
-    pass
+class BaseMetaAppliance(BaseMeta):
+
+    @classmethod
+    def pre_check(
+        mcs: type["BaseMeta"], name: str, bases: tuple[type[Any], ...], namespace: dict[str, Any]  # pylint: disable=unused-argument
+    ) -> None:
+        """early BaseElement checks"""
+        print("__NEW__ Defining:", name, "with keys:", list(namespace))
+        super().pre_check(name,bases,namespace)
+        if "features" not in namespace["__DABSchema__"]:
+            namespace["__DABSchema__"]["features"]={}
+        else:
+            namespace["__DABSchema__"]["features"] = copy(namespace["__DABSchema__"]["features"])
+        return
 
 
-class BaseAppliance(BaseElement):
-    pass
+    @classmethod
+    def pre_processing(mcs: type["BaseMeta"], name: str, bases: tuple[type[Any], ...], namespace: dict[str, Any]):
+        mcs.new_features: dict[str,type[BaseFeature]] = {}
+        mcs.modified_features: dict[str,type[BaseFeature]] = {}
+        super().pre_processing(name,bases,namespace)
+        
+    @classmethod
+    def pre_processing_new_fields(
+        mcs: type["BaseMeta"], name: str, bases: tuple[type[Any], ...], namespace: dict[str, Any], _fname: str, _fvalue: Any
+    ):  # pylint: disable=unused-argument
+        """preprocessing BaseElement new Fields"""
+        print('pre_processing_new_fields')
+        if _fname in namespace["__DABSchema__"]["features"].keys():
+            print("existing Feature !")
+            if not issubclass(_fvalue,namespace["__DABSchema__"]["features"][_fname]):
+                raise InvalidFeatureInheritance(f"Feature {_fname} is not an instance of {bases[0]}.{_fname}")
+            mcs.modified_features[_fname]=_fvalue
+        elif isinstance(_fvalue,BaseMetaFeature):
+            print("find Feature")
+            mcs.new_features[_fname]=_fvalue
+        else:
+            super().pre_processing_new_fields(name,bases,namespace,_fname,_fvalue)
+            
+    @classmethod
+    def save_values(
+        mcs: type["BaseMeta"], cls, name: str, bases: tuple[type[Any], ...], namespace: dict[str, Any]  # pylint: disable=unused-argument
+    ):
+        super().save_values(cls,name,bases,namespace)
+        print(dir(mcs))
+        for _ftname,_ftvalue in mcs.modified_features.items():
+            cls.__DABSchema__["features"][_ftname] = _ftvalue
+        for _ftname,_ftvalue in mcs.new_features.items():
+            cls.__DABSchema__["features"][_ftname] = _ftvalue
+    
+    def modify_object(cls:Type, obj):  # intentionally untyped
+        for _ftname,_ftvalue in cls.__DABSchema__["features"].items():
+            instft = _ftvalue()
+            object.__setattr__(obj, _ftname,instft )
+            
+    
+class BaseAppliance(BaseElement,metaclass=BaseMetaAppliance):
+    """BaseFeature class
+    Base class for Appliance.
+    An appliance is a server configuration / image that is built using appliance's code and Fields.
+    """

src/dabmodel/tools.py

@@ -1,13 +1,17 @@
+"""library's internal tools"""
+
 from uuid import UUID
 from datetime import datetime
 import json
 
 
 class DABJSONEncoder(json.JSONEncoder):
-    def default(self, obj):
-        if isinstance(obj, UUID):
-            # if the obj is uuid, we simply return the value of uuid
-            return obj.hex
-        elif isinstance(obj, datetime):
-            return str(obj)
-        return json.JSONEncoder.default(self, obj)
+    """allows to JSON encode non supported data type"""
+
+    def default(self, o):
+        if isinstance(o, UUID):
+            # if the o is uuid, we simply return the value of uuid
+            return o.hex
+        if isinstance(o, datetime):
+            return str(o)
+        return json.JSONEncoder.default(self, o)

test/test_model.py

@@ -15,6 +15,7 @@ from pathlib import Path
 import textwrap
 from typing import List, Optional, Dict, Union, Tuple, Set, FrozenSet, TypeVar, Generic, Any, Annotated
 from pprint import pprint
+from frozendict import frozendict
 
 print(__name__)
 print(__package__)
@@ -30,7 +31,7 @@ def test_initializer_safe_testfc():
     eval("print('hi')")
 
 
-class TestConfigWithoutEnabledFlag(unittest.TestCase):
+class MainTests(unittest.TestCase):
     def setUp(self):
         print("\n->", unittest.TestCase.id(self))
 
@@ -1040,11 +1041,11 @@ class TestConfigWithoutEnabledFlag(unittest.TestCase):
 
         app1 = Appliance1()
 
-        self.assertEquals(app1.VarInt, 12)
-        self.assertEquals(app1.VarInt2, 13)
-        self.assertEquals(app1.set1, frozenset({0}))
-        self.assertEquals(app1.set2, frozenset((1.43, 1234)))
-        self.assertEquals(app1.VarStr1, "ABCD")
+        self.assertEqual(app1.VarInt, 12)
+        self.assertEqual(app1.VarInt2, 13)
+        self.assertEqual(app1.set1, frozenset({0}))
+        self.assertEqual(app1.set2, frozenset((1.43, 1234)))
+        self.assertEqual(app1.VarStr1, "ABCD")
 
         # class can be created
         class _(dm.BaseAppliance):
@@ -1056,7 +1057,7 @@ class TestConfigWithoutEnabledFlag(unittest.TestCase):
                 cls.VarInt = cls.VarInt + 1
 
         app2 = _()
-        self.assertEquals(app2.VarInt, 42)
+        self.assertEqual(app2.VarInt, 42)
 
     def test_initializer_safe(self):
 
@@ -1155,24 +1156,198 @@ class TestConfigWithoutEnabledFlag(unittest.TestCase):
                 cls.set2 = {math.ceil(list(cls.set1)[0])}
 
         app2 = Appliance2()
-        self.assertEquals(app2.VarInt2, 56)
-        self.assertEquals(app2.VarFloat, 1)
-        self.assertEquals(app2.VarInt, 0)
-        self.assertEquals(app2.VarInt3, 4)
-        self.assertEquals(app2.VarInt4, 7)
-        self.assertEquals(app2.VarInt5, 4)
-        self.assertEquals(app2.list2, (0, 1, 2, 4))
-        self.assertEquals(app2.list3, (0, 1, 2, 3, 4))
-        self.assertEquals(app2.set2, {2})
+        self.assertEqual(app2.VarInt2, 56)
+        self.assertEqual(app2.VarFloat, 1)
+        self.assertEqual(app2.VarInt, 0)
+        self.assertEqual(app2.VarInt3, 4)
+        self.assertEqual(app2.VarInt4, 7)
+        self.assertEqual(app2.VarInt5, 4)
+        self.assertEqual(app2.list2, (0, 1, 2, 4))
+        self.assertEqual(app2.list3, (0, 1, 2, 3, 4))
+        self.assertEqual(app2.set2, {2})
 
-        class _(dm.BaseAppliance):
-            _: int = 0
+        with self.assertRaises(NameError):
 
-            @classmethod
-            def __initializer(cls):
-                test_initializer_safe_testfc()
+            class _(dm.BaseAppliance):
+                _: int = 0
+
+                @classmethod
+                def __initializer(cls):
+                    test_initializer_safe_testfc()
+
+    def test_feature(self):
+        """Testing first appliance feature, and Field types (simple)"""
 
 
+            
+        # class can be created
+        class Appliance1(dm.BaseAppliance):
+            VarStrOuter: str = "testvalue APPLIANCE"
+            class Feature1(dm.BaseFeature):
+                VarStrInner: str = "testvalue FEATURE"
+        app1 = Appliance1()
+               
+        self.assertIsInstance(Appliance1.__DABSchema__["VarStrOuter"],dm.DABField)
+        self.assertIsInstance(app1.__DABSchema__["VarStrOuter"],dm.FrozenDABField)
+        self.assertIn("Feature1",app1.__DABSchema__["features"])
+        self.assertIn("VarStrInner",app1.__DABSchema__["features"]["Feature1"].__DABSchema__)
+        self.assertIsInstance(app1.__DABSchema__["features"]["Feature1"].__DABSchema__["VarStrInner"],dm.DABField)
+        self.assertTrue(hasattr(app1, "Feature1"))
+        self.assertIsInstance(app1.Feature1.__DABSchema__["VarStrInner"],dm.FrozenDABField)
+        self.assertTrue(hasattr(app1.Feature1, "VarStrInner"))
+        
+    def test_feature_inheritance(self):
+        """Testing first appliance feature, and Field types (simple)"""
+
+
+            
+        # class can be created
+        class Appliance1(dm.BaseAppliance):
+            VarStrOuter: str = "testvalue APPLIANCE1"
+            class Feature1(dm.BaseFeature):
+                VarStrInner: str = "testvalue FEATURE1"
+                VarInt:int=42
+                
+        print(dir(Appliance1))
+        
+        class Appliance2(Appliance1):
+            VarStrOuter = "testvalue APPLIANCE2"
+            class Feature2(dm.BaseFeature):
+                VarStrInner: str = "testvalue FEATURE2"   
+                
+        print(dir(Appliance2))
+        
+        class Appliance3(Appliance2):
+            VarStrOuter = "testvalue APPLIANCE3"
+            class Feature1(Appliance1.Feature1):
+                VarStrInner = "testvalue FEATURE1 modded"
+            class Feature3(dm.BaseFeature):
+                VarStrInner: str = "testvalue FEATURE3"             
+                
+        print(dir(Appliance3))
+        
+        app1 = Appliance1()
+        app2 = Appliance2()
+        app3 = Appliance3()
+               
+        self.assertIsInstance(Appliance1.__DABSchema__["VarStrOuter"],dm.DABField)
+        self.assertIsInstance(app1.__DABSchema__["VarStrOuter"],dm.FrozenDABField)
+        self.assertIn("Feature1",app1.__DABSchema__["features"])
+        self.assertIn("VarStrInner",app1.__DABSchema__["features"]["Feature1"].__DABSchema__)
+        self.assertIsInstance(app1.__DABSchema__["features"]["Feature1"].__DABSchema__["VarStrInner"],dm.DABField)
+        self.assertTrue(hasattr(app1, "Feature1"))
+        self.assertIsInstance(app1.Feature1.__DABSchema__["VarStrInner"],dm.FrozenDABField)
+        self.assertTrue(hasattr(app1.Feature1, "VarStrInner"))
+        self.assertEqual(app1.VarStrOuter,"testvalue APPLIANCE1")
+        self.assertEqual(app1.Feature1.VarStrInner,"testvalue FEATURE1")
+        self.assertEqual(app1.Feature1.VarInt,42)
+        self.assertEqual(app2.VarStrOuter,"testvalue APPLIANCE2")
+        self.assertEqual(app2.Feature2.VarStrInner,"testvalue FEATURE2")
+        self.assertEqual(app3.VarStrOuter,"testvalue APPLIANCE3")
+        self.assertEqual(app3.Feature1.VarStrInner,"testvalue FEATURE1 modded")
+        self.assertEqual(app3.Feature1.VarInt,42)
+        self.assertEqual(app3.Feature3.VarStrInner,"testvalue FEATURE3")
+        
+    def test_feature_inheritance2(self):
+        """Testing first appliance feature, and Field types (simple)"""
+  
+        # class can be created
+        class Appliance1(dm.BaseAppliance):
+            class Feature1(dm.BaseFeature):
+                VarStrInner: str = "testvalue FEATURE1"
+        
+        # check cannot REdefine a feature from BaseFeature
+        with self.assertRaises(dm.InvalidFeatureInheritance):
+            class Appliance2(Appliance1):
+                class Feature1(dm.BaseFeature):
+                    ...
+                
+        class Appliance2b(Appliance1):
+            class Feature1(Appliance1.Feature1):
+                ...
+                
+        # check only REdefine a feature from direct parent
+        with self.assertRaises(dm.InvalidFeatureInheritance):
+            class Appliance3(Appliance2b):
+                class Feature1(Appliance1.Feature1):
+                    ...
+        
+        class Appliance3b(Appliance2b):
+            class Feature1(Appliance2b.Feature1):
+                ...
+
+        app1 = Appliance1()
+        app2 = Appliance2b()
+        
+        print("youhou1")    
+        print(Appliance3b)
+        print(Appliance3b.Feature1)
+        print("=====")
+        
+        app3 = Appliance3b()
+        
+        print("youhou2")  
+        print(Appliance3b)
+        print(Appliance3b.Feature1)
+        print("=====")
+                
+        #self.assertEqual(app1.Feature1.VarStrInner,"testvalue FEATURE1")
+        #self.assertEqual(app2.Feature1.VarStrInner,"testvalue FEATURE1")
+        #self.assertEqual(app3.Feature1.VarStrInner,"testvalue FEATURE1")
+
+        class Appliance4(Appliance3b):
+            class Feature1(Appliance3b.Feature1):
+                VarStrInner = "testvalue FEATURE4"
+        
+        self.assertEqual(app1.Feature1.VarStrInner,"testvalue FEATURE1")
+        self.assertEqual(app2.Feature1.VarStrInner,"testvalue FEATURE1")
+        self.assertEqual(app3.Feature1.VarStrInner,"testvalue FEATURE1")
+        
+        app4 = Appliance4()
+        
+        self.assertEqual(app1.Feature1.VarStrInner,"testvalue FEATURE1")
+        self.assertEqual(app2.Feature1.VarStrInner,"testvalue FEATURE1")
+        self.assertEqual(app3.Feature1.VarStrInner,"testvalue FEATURE1")
+        self.assertEqual(app4.Feature1.VarStrInner,"testvalue FEATURE4")
+        
+    def test_inheritance_chain(self):
+  
+        # class can be created
+        class Appliance1(dm.BaseAppliance):
+            VarStr: str = "testvalue1"
+            
+        class Appliance2(Appliance1):
+            pass
+            
+        class Appliance3(Appliance2):
+            pass
+        
+        app1 = Appliance1()
+        app2 = Appliance2()
+        app3 = Appliance3()
+        
+        self.assertEqual(app1.VarStr,"testvalue1")
+        self.assertEqual(app2.VarStr,"testvalue1")
+        self.assertEqual(app3.VarStr,"testvalue1")
+        
+        class Appliance4(Appliance3):
+            VarStr = "testvalue moded"
+        
+        
+        app4 = Appliance4()
+        
+        self.assertEqual(app1.VarStr,"testvalue1")
+        self.assertEqual(app2.VarStr,"testvalue1")
+        self.assertEqual(app3.VarStr,"testvalue1")
+        self.assertEqual(app4.VarStr,"testvalue moded")
+        
+        app1b = Appliance1()
+        app2b = Appliance2()
+        app3b = Appliance3()
+        self.assertEqual(app1b.VarStr,"testvalue1")
+        self.assertEqual(app2b.VarStr,"testvalue1")
+        self.assertEqual(app3b.VarStr,"testvalue1")
+        
 # ---------- main ----------
 
 if __name__ == "__main__":