continue renaming

into dev

pyproject.toml

@@ -35,8 +35,8 @@ classifiers = [
 dependencies = [
     'importlib-metadata; python_version<"3.9"',
     'packaging',
-    'pydantic',
-    'runtype'
+    'frozendict',
+    'typeguard'
 ]
 dynamic = ["version"]
 

src/dabmodel/LAMFields/Constraint.py

@@ -0,0 +1,17 @@
+from typing import Generic, TypeVar
+
+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: T_Field) -> bool:
+        """Check if a Constraint is completed"""
+        return True

src/dabmodel/LAMFields/FrozenLAMField.py

@@ -0,0 +1,41 @@
+from typing import Generic, TypeVar, Any
+
+from .LAMField import LAMField
+from .Constraint import BaseConstraint
+from ..tools import LAMdeepfreeze
+
+T_Field = TypeVar("T_Field")
+
+
+class FrozenLAMField(Generic[T_Field]):
+    """FrozenLAMField class
+    a read-only proxy of a Field
+    """
+
+    def __init__(self, inner_field: LAMField):
+        self._inner_field = inner_field
+
+    @property
+    def doc(self) -> str:
+        """Returns Field's documentation (frozen)"""
+        return LAMdeepfreeze(self._inner_field.doc)
+
+    @property
+    def constraints(self) -> tuple[BaseConstraint]:
+        """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

@@ -0,0 +1,62 @@
+from typing import Generic, TypeVar, Optional, Any
+
+from .LAMFieldInfo import LAMFieldInfo
+from .Constraint import BaseConstraint
+from ..tools import LAMdeepfreeze
+
+T_Field = TypeVar("T_Field")
+
+
+class LAMField(Generic[T_Field]):
+    """This class describe a Field in Schema"""
+
+    def __init__(self, name: str, v: Optional[T_Field], a: Any, i: LAMFieldInfo):
+        self._name: str = name
+        self._source: Optional[type] = None
+        self._default_value: Optional[T_Field] = v
+        self._value: Optional[T_Field] = v
+        self._annotations: Any = a
+        self._info: LAMFieldInfo = i
+        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) -> 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) -> Any:
+        """Returns Field's default value (frozen)"""
+        return LAMdeepfreeze(self._default_value)
+
+    def update_value(self, v: Optional[T_Field] = None) -> None:
+        """Updates Field's value"""
+        self._value = v
+
+    @property
+    def value(self) -> Any:
+        """Returns Field's value (frozen)"""
+        return LAMdeepfreeze(self._value)
+
+    @property
+    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

src/dabmodel/LAMFields/LAMFieldInfo.py

@@ -0,0 +1,26 @@
+from typing import Optional, Any
+from .Constraint import BaseConstraint
+
+
+class LAMFieldInfo:
+    """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]
+        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[BaseConstraint[Any]]:
+        """Returns Field's constraints"""
+        return self._constraints

src/dabmodel/__init__.py

@@ -11,4 +11,28 @@ Main module __init__ file.
 """
 
 from .__metadata__ import __version__, __Summuary__, __Name__
-from .model import  BaseFeature, BaseAppliance
+
+
+from .LAMFields.LAMField import LAMField
+from .LAMFields.LAMFieldInfo import LAMFieldInfo
+from .LAMFields.FrozenLAMField import FrozenLAMField
+from .appliance import Appliance
+from .feature import Feature
+
+
+from .exception import (
+    DABModelException,
+    MultipleInheritanceForbidden,
+    BrokenInheritance,
+    ReadOnlyField,
+    NewFieldForbidden,
+    NotAnnotatedField,
+    ReadOnlyFieldAnnotation,
+    InvalidFieldValue,
+    InvalidFieldAnnotation,
+    IncompletelyAnnotatedField,
+    ImportForbidden,
+    FunctionForbidden,
+    InvalidFeatureInheritance,
+    FeatureNotBound,
+)

src/dabmodel/__metadata__.py

@@ -15,20 +15,26 @@ import warnings
 
 try:  # pragma: no cover
     __version__ = version("dabmodel")
-except PackageNotFoundError: # pragma: no cover
-    warnings.warn("can not read __version__, assuming local test context, setting it to ?.?.?")
+except PackageNotFoundError:  # pragma: no cover
+    warnings.warn(
+        "can not read __version__, assuming local test context, setting it to ?.?.?"
+    )
     __version__ = "?.?.?"
 
 try:  # pragma: no cover
     dist = distribution("dabmodel")
     __Summuary__ = dist.metadata["Summary"]
 except PackageNotFoundError:  # pragma: no cover
-    warnings.warn('can not read dist.metadata["Summary"], assuming local test context, setting it to <dabmodel description>')
+    warnings.warn(
+        'can not read dist.metadata["Summary"], assuming local test context, setting it to <dabmodel description>'
+    )
     __Summuary__ = "dabmodel description"
 
 try:  # pragma: no cover
     dist = distribution("dabmodel")
     __Name__ = dist.metadata["Name"]
 except PackageNotFoundError:  # pragma: no cover
-    warnings.warn('can not read dist.metadata["Name"], assuming local test context, setting it to <dabmodel>')
+    warnings.warn(
+        'can not read dist.metadata["Name"], assuming local test context, setting it to <dabmodel>'
+    )
     __Name__ = "dabmodel"

src/dabmodel/appliance.py

@@ -0,0 +1,9 @@
+from .element import Element
+from .meta.appliance import _MetaAppliance
+
+
+class Appliance(Element, metaclass=_MetaAppliance):
+    """BaseFeature class
+    Base class for Appliance.
+    An appliance is a server configuration / image that is built using appliance's code and Fields.
+    """

src/dabmodel/element.py

@@ -0,0 +1,7 @@
+from .meta.base import _MetaElement
+
+
+class Element(metaclass=_MetaElement):
+    """Element class
+    Base class to apply metaclass and set common Fields.
+    """

src/dabmodel/exception.py

@@ -0,0 +1,103 @@
+class DABModelException(Exception):
+    """DABModelException Exception class
+    Base Exception for DABModelException class
+    """
+
+
+class FunctionForbidden(DABModelException): ...
+
+
+class ExternalCodeForbidden(FunctionForbidden): ...
+
+
+class ClosureForbidden(FunctionForbidden): ...
+
+
+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 BrokenInheritance(DABModelException):
+    """BrokenInheritance Exception class
+    inheritance chain is broken
+    """
+
+
+class ReadOnlyField(DABModelException):
+    """ReadOnlyField Exception class
+    The used Field is ReadOnly
+    """
+
+
+class NewFieldForbidden(DABModelException):
+    """NewFieldForbidden Exception class
+    Field creation is forbidden
+    """
+
+
+class InvalidFieldAnnotation(DABModelException):
+    """InvalidFieldAnnotation Exception class
+    The field annotation is invalid
+    """
+
+
+class InvalidInitializerType(DABModelException):
+    """InvalidInitializerType Exception class
+    The initializer is not a valid type
+    """
+
+
+class NotAnnotatedField(InvalidFieldAnnotation):
+    """NotAnnotatedField Exception class
+    The Field is not Annotated
+    """
+
+
+class IncompletelyAnnotatedField(InvalidFieldAnnotation):
+    """IncompletelyAnnotatedField Exception class
+    The field annotation is incomplete
+    """
+
+
+class ReadOnlyFieldAnnotation(DABModelException):
+    """ReadOnlyFieldAnnotation Exception class
+    Field annotation connot be modified
+    """
+
+
+class InvalidFieldValue(DABModelException):
+    """InvalidFieldValue Exception class
+    The Field value is invalid
+    """
+
+
+class NonExistingField(DABModelException):
+    """NonExistingField Exception class
+    The given Field is non existing
+    """
+
+
+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 FeatureNotBound(DABModelException):
+    """FeatureNotBound Exception class
+    a Feature must be bound to the appliance (or parent)
+    """

src/dabmodel/feature.py

@@ -0,0 +1,12 @@
+from .element import Element
+from .meta.feature import _MetaFeature
+
+
+class Feature(Element, metaclass=_MetaFeature):
+    """Feature class
+    Base class for Appliance's Features.
+    Features are optional traits of an appliance.
+    """
+
+    _BoundAppliance: "Optional[Type[BaseAppliance]]" = None
+    Enabled: bool = False

src/dabmodel/meta/appliance.py

@@ -0,0 +1,235 @@
+from typing import Any, Type
+from copy import copy
+
+from typeguard import check_type, CollectionCheckStrategy, TypeCheckError
+
+from ..tools import LAMdeepfreeze
+from ..LAMFields.LAMField import LAMField
+from ..LAMFields.FrozenLAMField import FrozenLAMField
+from .base import _MetaElement
+from ..feature import Feature
+from ..exception import (
+    InvalidFieldValue,
+    InvalidFeatureInheritance,
+    FeatureNotBound,
+)
+
+
+class _MetaAppliance(_MetaElement):
+    """_MetaAppliance class
+    Appliance specific metaclass code
+    """
+
+    @classmethod
+    def check_class(
+        mcs: type["meta"],
+        name: str,
+        bases: tuple[type[Any], ...],
+        namespace: dict[str, Any],  # pylint: disable=unused-argument
+        extensions: dict[str, Any],
+    ) -> None:
+        """
+        Appliance-specific pre-check: ensure the `features` slot exists in schema.
+
+        Copies the parent's `features` mapping when inheriting to keep it per-class.
+        """
+        super().check_class(name, bases, namespace, extensions)  # type: ignore[misc]
+        if "features" not in namespace["__DABSchema__"]:
+            namespace["__DABSchema__"]["features"] = {}
+        else:
+            namespace["__DABSchema__"]["features"] = copy(
+                namespace["__DABSchema__"]["features"]
+            )
+
+    @classmethod
+    def process_class_fields(
+        mcs: type["meta"],
+        name: str,
+        bases: tuple[type[Any], ...],
+        namespace: dict[str, Any],
+        extensions: dict[str, Any],
+    ):
+        """
+        Like meta.process_class_fields but also stages Feature declarations.
+
+        Initializes:
+          extensions["new_features"], extensions["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]
+
+    @classmethod
+    def process_new_field(
+        mcs: type["meta"],
+        name: str,
+        bases: tuple[type[Any], ...],
+        namespace: dict[str, Any],
+        _fname: str,
+        _fvalue: Any,
+        extensions: dict[str, Any],
+    ):  # pylint: disable=unused-argument
+        """
+        Intercept Feature declarations.
+
+        - If `_fname` already exists in parent's `features`, enforce same type;
+          stage into `modified_features`.
+        - Else, if `_fvalue` is a Feature *class*, stage into `new_features`.
+        - Otherwise, it is a regular field: delegate to meta.process_new_field.
+        """
+        if _fname in namespace["__DABSchema__"]["features"].keys():
+            if not issubclass(_fvalue, namespace["__DABSchema__"]["features"][_fname]):
+                raise InvalidFeatureInheritance(
+                    f"Feature {_fname} is not an instance of {bases[0]}.{_fname}"
+                )
+            extensions["modified_features"][_fname] = _fvalue
+        elif isinstance(_fvalue, type) and issubclass(_fvalue, Feature):
+            extensions["new_features"][_fname] = _fvalue
+        else:
+            super().process_new_field(name, bases, namespace, _fname, _fvalue, extensions)  # type: ignore[misc]
+
+    @classmethod
+    def commit_fields(
+        mcs: type["meta"],
+        cls,
+        name: str,
+        bases: tuple[type[Any], ...],
+        namespace: dict[str, Any],  # pylint: disable=unused-argument
+        extensions: dict[str, Any],
+    ):
+        """
+        Commit regular fields (via meta) and then bind staged Feature classes.
+
+        For each new/modified feature:
+          - bind it to `cls` (sets the feature's `_BoundAppliance`),
+          - register it under `cls.__DABSchema__["features"]`.
+        """
+        super().commit_fields(cls, name, bases, namespace, extensions)  # type: ignore[misc]
+
+        for _ftname, _ftvalue in extensions["modified_features"].items():
+            _ftvalue._BoundAppliance = cls  # pylint: disable=protected-access
+            cls.__DABSchema__["features"][_ftname] = _ftvalue
+        for _ftname, _ftvalue in extensions["new_features"].items():
+            _ftvalue._BoundAppliance = cls  # pylint: disable=protected-access
+            cls.__DABSchema__["features"][_ftname] = _ftvalue
+
+    def finalize_instance(cls: Type, obj, extensions: dict[str, Any]):
+        """
+        Instantiate and attach all features declared (or overridden) in the instance schema.
+        Handles:
+          - Declared features (plain class)
+          - Subclass replacements
+          - Dict overrides (class + patch dict)
+        """
+        for fname, fdef in obj.__DABSchema__.get("features", {}).items():
+            # Case 1: plain class or subclass
+            if isinstance(fdef, type) and issubclass(fdef, Feature):
+                inst = fdef()
+                object.__setattr__(obj, fname, 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.__DABSchema__:
+                        raise InvalidFieldValue(
+                            f"Feature '{fname}' has no field '{field_name}'"
+                        )
+                    field = feat_cls.__DABSchema__[field_name]
+                    try:
+                        check_type(
+                            new_val,
+                            field.annotations,
+                            collection_check_strategy=CollectionCheckStrategy.ALL_ITEMS,
+                        )
+                    except TypeCheckError as exp:
+                        raise InvalidFieldValue(
+                            f"Invalid value for {fname}.{field_name}: "
+                            f"expected {field.annotations}, got {new_val!r}"
+                        ) from exp
+                    object.__setattr__(inst, field_name, LAMdeepfreeze(new_val))
+                    inst.__DABSchema__[field_name] = FrozenLAMField(
+                        LAMField(field_name, new_val, field.annotations, field._info)
+                    )
+                object.__setattr__(obj, fname, inst)
+
+            else:
+                raise InvalidFieldValue(
+                    f"Invalid feature definition stored for '{fname}': {fdef!r}"
+                )
+
+    def apply_overrides(cls, obj, extensions, *args, **kwargs):
+        """
+        Support for runtime field and feature overrides.
+
+        Fields:
+          MyApp(name="foo")
+
+        Features:
+          MyApp(F1=MyF1)                # inheritance / replacement
+          MyApp(F1={"val": 42, ...})    # dict override of existing feature
+        """
+        # --- field overrides (unchanged) ---
+        for k, v in list(kwargs.items()):
+            if k in cls.__DABSchema__:  # regular field
+                field = cls.__DABSchema__[k]
+                try:
+                    check_type(
+                        v,
+                        field.annotations,
+                        collection_check_strategy=CollectionCheckStrategy.ALL_ITEMS,
+                    )
+                except TypeCheckError as exp:
+                    raise InvalidFieldValue(
+                        f"Invalid value for field '{k}': expected {field.annotations}, got {v!r}"
+                    ) from exp
+
+                object.__setattr__(obj, k, LAMdeepfreeze(v))
+                obj.__DABSchema__[k] = FrozenLAMField(
+                    LAMField(k, v, field.annotations, field._info)
+                )
+                kwargs.pop(k)
+
+        # --- feature overrides ---
+        for k, v in list(kwargs.items()):
+            if k in cls.__DABSchema__.get("features", {}):
+                base_feat_cls = cls.__DABSchema__["features"][k]
+
+                # Case 1: subclass replacement (inheritance)
+                if isinstance(v, type) and issubclass(v, base_feat_cls):
+                    bound = getattr(v, "_BoundAppliance", None)
+                    if bound is None or not issubclass(cls, bound):
+                        raise FeatureNotBound(
+                            f"Feature {v.__name__} is not bound to {cls.__name__}"
+                        )
+                    # record subclass into instance schema
+                    obj.__DABSchema__["features"][k] = v
+                    kwargs.pop(k)
+
+                # Case 2: dict override
+                elif isinstance(v, dict):
+                    # store (class, override_dict) for finalize_instance
+                    obj.__DABSchema__["features"][k] = (base_feat_cls, v)
+                    kwargs.pop(k)
+
+                else:
+                    raise InvalidFieldValue(
+                        f"Feature override for '{k}' must be a Feature subclass or dict, got {type(v)}"
+                    )
+
+        # --- new features not declared at class level ---
+        for k, v in list(kwargs.items()):
+            if isinstance(v, type) and issubclass(v, Feature):
+                bound = getattr(v, "_BoundAppliance", None)
+                if bound is None or not issubclass(cls, bound):
+                    raise FeatureNotBound(
+                        f"Feature {v.__name__} is not bound to {cls.__name__}"
+                    )
+                obj.__DABSchema__["features"][k] = v
+                kwargs.pop(k)
+
+        if kwargs:
+            unknown = ", ".join(sorted(kwargs.keys()))
+            raise InvalidFieldValue(f"Unknown parameters: {unknown}")

src/dabmodel/meta/base.py

@@ -0,0 +1,749 @@
+from typing import (
+    Optional,
+    TypeVar,
+    Union,
+    get_origin,
+    get_args,
+    List,
+    Dict,
+    Any,
+    Tuple,
+    Set,
+    Annotated,
+    FrozenSet,
+    Callable,
+    Type,
+)
+
+from types import UnionType, FunctionType, SimpleNamespace
+from copy import deepcopy, copy
+
+import math
+import inspect, ast, textwrap
+
+from typeguard import check_type, TypeCheckError, CollectionCheckStrategy
+
+from ..LAMFields.LAMField import LAMField
+from ..LAMFields.LAMFieldInfo import LAMFieldInfo
+from ..LAMFields.FrozenLAMField import FrozenLAMField
+
+from ..exception import (
+    MultipleInheritanceForbidden,
+    BrokenInheritance,
+    ReadOnlyField,
+    NewFieldForbidden,
+    NotAnnotatedField,
+    ReadOnlyFieldAnnotation,
+    InvalidFieldValue,
+    InvalidFieldAnnotation,
+    IncompletelyAnnotatedField,
+    ImportForbidden,
+    FunctionForbidden,
+    NonExistingField,
+    InvalidInitializerType,
+)
+
+ALLOWED_ANNOTATIONS: dict[str, Any] = {
+    "Union": Union,
+    "Optional": Optional,
+    "List": List,
+    "Dict": Dict,
+    "Tuple": Tuple,
+    "Set": Set,
+    "FrozenSet": FrozenSet,
+    "Annotated": Annotated,
+    # builtins:
+    "int": int,
+    "str": str,
+    "float": float,
+    "bool": bool,
+    "complex": complex,
+    "bytes": bytes,
+    "None": type(None),
+    "list": list,
+    "dict": dict,
+    "set": set,
+    "frozenset": frozenset,
+    "tuple": tuple,
+}
+ALLOWED_MODEL_FIELDS_TYPES: tuple[type[Any], ...] = (
+    str,
+    int,
+    float,
+    complex,
+    bool,
+    bytes,
+)
+
+
+ALLOWED_HELPERS_MATH = SimpleNamespace(
+    sqrt=math.sqrt,
+    floor=math.floor,
+    ceil=math.ceil,
+    trunc=math.trunc,
+    fabs=math.fabs,
+    copysign=math.copysign,
+    hypot=math.hypot,
+    exp=math.exp,
+    log=math.log,
+    log10=math.log10,
+    sin=math.sin,
+    cos=math.cos,
+    tan=math.tan,
+    atan2=math.atan2,
+    radians=math.radians,
+    degrees=math.degrees,
+)
+
+ALLOWED_HELPERS_DEFAULT: dict[str, object] = {
+    "math": ALLOWED_HELPERS_MATH,
+    "print": print,
+    # Numbers & reducers (pure, deterministic)
+    "abs": abs,
+    "round": round,
+    "min": min,
+    "max": max,
+    "sum": sum,
+    # Introspection-free basics
+    "len": len,
+    "sorted": sorted,
+    # Basic constructors (for copy-on-write patterns)
+    "tuple": tuple,
+    "list": list,
+    "dict": dict,
+    "set": set,
+    # Simple casts if they need to normalize types
+    "int": int,
+    "float": float,
+    "str": str,
+    "bool": bool,
+    "bytes": bytes,
+    "complex": complex,
+    # Easy iteration helpers (optional but handy)
+    "range": range,
+}
+
+
+def _check_initializer_safety(func) -> None:
+    """
+    Preliminary structural check for __initializer__.
+
+    Policy (minimal):
+      - Forbid 'import' / 'from ... import ...' inside the initializer body.
+      - Forbid nested function definitions (closures/helpers) in the body.
+      - Allow lambdas.
+      - No restrictions on calls here (keep it simple).
+      - Optionally forbid closures (free vars) for determinism.
+    """
+    try:
+        src = inspect.getsource(func)
+    except OSError as exc:
+        # If source isn't available (rare), fail closed (or skip if you prefer)
+        raise FunctionForbidden("Cannot inspect __initializer__ source") from exc
+
+    src = textwrap.dedent(src)
+    mod = ast.parse(src)
+
+    # Find the FunctionDef node that corresponds to this initializer
+    init_node = None
+    for n in mod.body:
+        if (
+            isinstance(n, (ast.FunctionDef, ast.AsyncFunctionDef))
+            and n.name == func.__name__
+        ):
+            init_node = n
+            break
+    if init_node is None:
+        # Fallback: if not found, analyze nothing further to avoid false positives
+        return
+
+    # Walk ONLY the body of the initializer (don't flag the def itself)
+    body_tree = ast.Module(body=init_node.body, type_ignores=[])
+
+    for node in ast.walk(body_tree):
+        # Forbid imports
+        if isinstance(node, (ast.Import, ast.ImportFrom)):
+            raise ImportForbidden("imports disabled in __initializer")
+
+        # Forbid nested defs (but allow lambdas)
+        if isinstance(node, (ast.FunctionDef, ast.AsyncFunctionDef)):
+            raise FunctionForbidden(
+                "Nested function definitions are forbidden in __initializer"
+            )
+
+        if isinstance(node, ast.Lambda):  # Forbid lambda
+            raise FunctionForbidden("Lambdas are forbidden in __initializer")
+
+    # Optional: forbid closures (keeps determinism; allows lambdas that don't capture)
+    if func.__code__.co_freevars:
+        raise FunctionForbidden("Closures are forbidden in __initializer__")
+
+
+def _blocked_import(*args, **kwargs):
+    raise ImportForbidden("imports disabled in __initializer")
+
+
+def _resolve_annotation(ann):
+    if isinstance(ann, str):
+        # Safe eval against a **whitelist** only
+        return eval(  # pylint: disable=eval-used
+            ann, {"__builtins__": {}}, ALLOWED_ANNOTATIONS
+        )
+    return ann
+
+
+def _peel_annotated(t: Any) -> Any:
+    # If you ever allow Annotated[T, ...], peel to T
+    while True:
+        origin = get_origin(t)
+        if origin is None:
+            return t
+        name = (
+            getattr(origin, "__name__", "")
+            or getattr(origin, "__qualname__", "")
+            or str(origin)
+        )
+        if "Annotated" in name:
+            args = get_args(t)
+            t = args[0] if args else t
+        else:
+            return t
+
+
+def _check_annotation_definition(  # pylint: disable=too-complex,too-many-return-statements
+    _type,
+) -> bool:
+    _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)
+        )
+
+    # 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))
+
+    # handle Dict[...]
+    if get_origin(_type) is dict:
+        inner = get_args(_type)
+        if len(inner) != 2:
+            raise IncompletelyAnnotatedField(
+                f"Dict Annotation requires 2 inner definitions: {_type}"
+            )
+        return _peel_annotated(
+            inner[0]
+        ) in ALLOWED_MODEL_FIELDS_TYPES and _check_annotation_definition(inner[1])
+
+    # handle Tuple[]
+    if get_origin(_type) in [tuple]:
+        inner_types = get_args(_type)
+        if len(inner_types) == 0:
+            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)
+
+    # 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)
+
+    if _type in ALLOWED_MODEL_FIELDS_TYPES:
+        return True
+    return False
+
+
+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[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, "_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
+
+    @__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: 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)
+
+
+T_Meta = TypeVar("T_Meta", bound="_MetaElement")
+T_BE = TypeVar("T_BE", bound="BaseElement")
+
+
+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
+    __DABSchema__: dict[str, Any] = {}
+
+    @classmethod
+    def check_class(
+        mcs: type["_MetaElement"],
+        name: str,
+        bases: tuple[type[Any], ...],
+        namespace: dict[str, Any],  # pylint: disable=unused-argument
+        extensions: dict[str, Any],
+    ) -> None:
+        """
+        Early class-build hook.
+
+        Validates the inheritance shape, initializes an empty schema for root classes,
+        copies the parent schema for subclasses, and ensures all annotated fields
+        have a default (inserting `None` when missing).
+
+        This runs before the class object is created.
+        """
+        # print("__NEW__ Defining:", name, "with keys:", list(namespace))
+
+        if len(bases) > 1:
+            raise MultipleInheritanceForbidden(
+                "Multiple inheritance is not supported by dabmodel"
+            )
+        if len(bases) == 0:  # base class (BaseElement)
+            namespace["__DABSchema__"] = {}
+        else:  # standard inheritance
+            # check class tree origin
+            if "__DABSchema__" not in dir(bases[0]):
+                raise BrokenInheritance(
+                    "__DABSchema__ not found in base class, broken inheritance chain."
+                )
+            # copy inherited schema
+            namespace["__DABSchema__"] = copy(bases[0].__DABSchema__)
+
+        # force field without default value to be instantiated (with None)
+        if "__annotations__" in namespace:
+            for _funknown in [
+                _ for _ in namespace["__annotations__"] if _ not in namespace.keys()
+            ]:
+                namespace[_funknown] = None
+
+    @classmethod
+    def process_class_fields(  # pylint: disable=too-complex,too-many-branches
+        mcs: type["_MetaElement"],
+        name: str,
+        bases: tuple[type[Any], ...],
+        namespace: dict[str, Any],
+        extensions: dict[str, Any],
+    ):
+        """
+        Scan the class namespace and partition fields.
+
+        Detects:
+          - modified fields (shadowing parent values),
+          - new fields (present in annotations),
+          - the optional `__initializer` classmethod (in mangled or unmangled form).
+
+        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
+        to be committed later.
+        """
+        # iterating new and modified fields
+        mcs.modified_fields = {}
+        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()
+                mcs.initializer = _fvalue.__func__
+                if name.startswith("_"):
+                    initializer_name = "__initializer"
+                else:
+                    initializer_name = f"_{name}__initializer"
+            elif _fname.startswith("_"):
+                pass
+            elif isinstance(_fvalue, classmethod):
+                pass
+            else:
+                print(f"Parsing Field: {_fname} / {_fvalue}")
+                if (
+                    len(bases) == 1 and _fname in namespace["__DABSchema__"].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:
+            del namespace[initializer_name]
+
+    @classmethod
+    def process_modified_field(
+        mcs: type["_MetaElement"],
+        name: str,
+        bases: tuple[type[Any], ...],
+        namespace: dict[str, Any],
+        _fname: str,
+        _fvalue: Any,
+        extensions: 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`.
+        """
+        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_fields[_fname] = _fvalue
+
+    @classmethod
+    def process_new_field(
+        mcs: type["_MetaElement"],
+        name: str,
+        bases: tuple[type[Any], ...],
+        namespace: dict[str, Any],
+        _fname: str,
+        _fvalue: Any,
+        extensions: 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`.
+        """
+        # print(f"New field: {_fname}")
+
+        # 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: LAMFieldInfo = LAMFieldInfo()
+        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], LAMFieldInfo):
+                    raise InvalidFieldAnnotation(
+                        "Only LAMFieldInfo object is allowed as Annotated data."
+                    )
+
+                _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] = LAMField(
+            _fname, _fvalue, namespace["__annotations__"][_fname], _finfo
+        )
+
+    @classmethod
+    def apply_initializer(
+        mcs: type["_MetaElement"],
+        cls,
+        name: str,
+        bases: tuple[type[Any], ...],
+        namespace: dict[str, Any],  # pylint: disable=unused-argument
+        extensions: dict[str, Any],
+    ):
+        """
+        Apply the optional `__initializer` classmethod to compute derived defaults.
+
+        The initializer runs in a restricted, import-blocked environment using a
+        `ModelSpecView` proxy that enforces type checking on assignments.
+        On success, the computed values are validated and written back into the
+        class schema's DABFields.
+        """
+        if mcs.initializer is not None:
+            _check_initializer_safety(mcs.initializer)
+            init_fieldvalues = {}
+            init_fieldtypes = {}
+            for _fname, _fvalue in cls.__DABSchema__.items():
+                if isinstance(_fvalue, LAMField):
+                    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 mcs.initializer.__code__.co_freevars:
+                raise FunctionForbidden("__initializer must not use closures")
+            safe_initializer = FunctionType(
+                mcs.initializer.__code__,
+                safe_globals,
+                name=mcs.initializer.__name__,
+                argdefs=mcs.initializer.__defaults__,
+                closure=None,
+            )
+            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,
+                    )
+                except TypeCheckError as exp:
+                    raise InvalidFieldValue(
+                        f"Value of Field <{_fname}> is not of expected type {namespace['__annotations__'][_fname]}."
+                    ) from exp
+                cls.__DABSchema__[_fname].update_value(_fvalue)
+
+    def __new__(
+        mcs: type["_MetaElement"],
+        name: str,
+        bases: tuple[type[Any], ...],
+        namespace: dict[str, Any],
+    ) -> Type:
+        """BaseElement new class"""
+        extensions: dict[str, Any] = {}
+        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)
+        _cls.install_instance_guard(extensions)
+
+        return _cls
+
+    @classmethod
+    def commit_fields(
+        mcs: type["_MetaElement"],
+        cls,
+        name: str,
+        bases: tuple[type[Any], ...],
+        namespace: dict[str, Any],  # pylint: disable=unused-argument
+        extensions: dict[str, Any],
+    ):
+        """
+        Commit staged fields into the class schema (`__DABSchema__`).
+
+        - 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.__DABSchema__[_fname] = deepcopy(bases[0].__DABSchema__[_fname])
+            cls.__DABSchema__[_fname].update_value(_fvalue)
+
+        for _fname, _fvalue in mcs.new_fields.items():
+            _fvalue.add_source(cls)
+            cls.__DABSchema__[_fname] = _fvalue
+
+    def __call__(cls: Type, *args: Any, **kw: Any):  # intentionally untyped
+        """BaseElement new instance"""
+        obj = super().__call__(*args)
+
+        extensions: dict[str, Any] = {}
+
+        cls.populate_instance(  # pylint: disable=no-value-for-parameter
+            obj, extensions, *args, **kw
+        )
+        cls.freeze_instance_schema(  # pylint: disable=no-value-for-parameter
+            obj, extensions, *args, **kw
+        )
+        cls.apply_overrides(  # pylint: disable=no-value-for-parameter
+            obj, extensions, *args, **kw
+        )
+        cls.finalize_instance(obj, extensions)  # pylint: disable=no-value-for-parameter
+
+        return obj
+
+    def populate_instance(
+        cls: Type, obj: Any, extensions: 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.__DABSchema__.items():
+            if isinstance(_fvalue, LAMField):
+                object.__setattr__(obj, _fname, _fvalue.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 `__DABSchema__` dict where each field is read-only.
+        """
+        inst_schema = copy(obj.__DABSchema__)
+        for _fname, _fvalue in cls.__DABSchema__.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, "__DABSchema__", inst_schema)
+
+    def apply_overrides(cls, obj, extensions, *args, **kwargs):
+        """
+        Hook for runtime overrides at instance creation.
+
+        Invoked after the schema has been frozen but before finalize_instance.
+        Subclasses of _MetaElement can override this to support things like:
+
+          - Field overrides: MyApp(field=value)
+          - Feature overrides: MyApp(FeatureName=CustomFeature)
+          - Feature attachments: MyApp(NewFeature=FeatureClass)
+
+        By default this does nothing.
+        """
+
+    def finalize_instance(cls: Type, obj: Any, extensions: dict[str, Any]):
+        """
+        Finalization hook invoked at the end of instance construction.
+
+        Subclasses of the metaclass override this to attach runtime components
+        to the instance. (Example: BaseMetaAppliance instantiates bound Features
+        and sets them as attributes on the appliance instance.)
+        """
+
+    def install_instance_guard(cls: Type, extensions: dict[str, Any]):
+        """
+        Install the runtime `__setattr__` guard on the class.
+
+        After instances are constructed, prevents:
+          - creating new public fields,
+          - reassigning existing fields post-initialization.
+
+        Private/dunder attributes are exempt to allow internal bookkeeping.
+        """
+        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)

src/dabmodel/meta/feature.py

@@ -0,0 +1,19 @@
+from typing import Type, Any
+from .base import _MetaElement
+from ..exception import FeatureNotBound
+
+
+class _MetaFeature(_MetaElement):
+    """_MetaFeature class
+    Feature specific metaclass code
+    """
+
+    def __call__(cls: Type, *args: Any, **kw: Any):  # intentionally untyped
+        """BaseFeature new instance"""
+
+        if cls._BoundAppliance is None:
+            raise FeatureNotBound()
+
+        obj = super().__call__(*args, **kw)
+
+        return obj

src/dabmodel/model.py

@@ -1,383 +0,0 @@
-from __future__ import annotations
-from typing import Any, Dict, Optional, TypeVar, Generic, get_origin, get_args, Annotated as _Annotated, Union
-
-from uuid import uuid4, UUID
-from datetime import datetime as _dt
-
-from pydantic import (
-    BaseModel,
-    Field,
-    ConfigDict,
-    model_validator,
-    AwareDatetime,
-    UUID4,
-    ByteSize,
-    StrictInt,
-    StrictStr,
-)
-from pydantic._internal._model_construction import ModelMetaclass
-import pytz
-
-
-# ===================== Maintainers’ policy =====================
-
-ALLOWED_APPLIANCE_FIELD_TYPES: set[type] = {
-    StrictInt, StrictStr, ByteSize, UUID4, UUID, AwareDatetime, _dt, bool, int, str,
-}
-ALLOWED_FEATURE_FIELD_TYPES: set[type] = {
-    StrictInt, StrictStr, ByteSize, UUID4, UUID, AwareDatetime, _dt, bool, int, str,
-}
-
-
-def _is_allowed_type(annotation: Any, allowed: set[type]) -> bool:
-    origin = get_origin(annotation)
-    if origin is _Annotated or (origin is not None and getattr(origin, "__name__", "") == "Annotated"):
-        return _is_allowed_type(get_args(annotation)[0], allowed)
-    if origin is None:
-        return annotation in allowed
-    if origin is Union:
-        args = [a for a in get_args(annotation) if a is not type(None)]
-        return all(_is_allowed_type(a, allowed) for a in args)
-    args = get_args(annotation)
-    if origin in (list, tuple, dict, set):
-        return all(_is_allowed_type(a, allowed) for a in args if a is not None)
-    return all(_is_allowed_type(a, allowed) for a in args if a is not None)
-
-
-def _is_feature_annotation(annotation: Any) -> bool:
-    origin = get_origin(annotation)
-    if origin is Union:
-        args = [a for a in get_args(annotation) if a is not type(None)]
-        return any(_is_feature_annotation(a) for a in args)
-    base = get_args(annotation)[0] if get_origin(annotation) is Optional else annotation
-    try:
-        return isinstance(base, type) and issubclass(base, BaseFeature)  # type: ignore[name-defined]
-    except Exception:
-        return False
-
-
-def _annotation_equal(a: Any, b: Any) -> bool:
-    oa, ob = get_origin(a), get_origin(b)
-    if oa is None and ob is None:
-        return a is b
-    if oa != ob:
-        return False
-    aa, ab = get_args(a), get_args(b)
-    if len(aa) != len(ab):
-        return False
-    return all(_annotation_equal(x, y) for x, y in zip(aa, ab))
-
-
-# ===================== Defaults mini-DSL (values only) =====================
-
-class _DefaultsSpec:
-    __slots__ = ("mapping",)
-    def __init__(self, mapping: Dict[str, Any]): self.mapping = mapping
-
-
-def defaults(**kwargs) -> _DefaultsSpec:
-    """
-    Declare class defaults in a flat mapping (values only).
-    Supports '.' or '__' for nesting:
-       Defaults = defaults(
-           template_short_name="apx",
-           Network__enabled=True,
-           Network__mtu=9000,
-       )
-    """
-    return _DefaultsSpec(kwargs)
-
-
-def _split_path(key: str) -> list[str]:
-    return key.replace("__", ".").split(".")
-
-
-def _merge_path(target: Dict[str, Any], path: str, value: Any):
-    parts = _split_path(path)
-    node = target
-    for i, p in enumerate(parts):
-        if i == len(parts) - 1:
-            node[p] = value
-        else:
-            node = node.setdefault(p, {})  # type: ignore[assignment]
-
-
-def _flatten_defaults_class(cls: type) -> Dict[str, Any]:
-    out: Dict[str, Any] = {}
-    for name, val in vars(cls).items():
-        if name.startswith("__"): 
-            continue
-        if isinstance(val, type):
-            sub = _flatten_defaults_class(val)
-            for k, v in sub.items():
-                out[f"{name}.{k}"] = v
-        else:
-            out[name] = val
-    return out
-
-
-def _deep_merge(dst: Dict[str, Any], src: Dict[str, Any]):
-    for k, v in src.items():
-        if isinstance(v, dict) and isinstance(dst.get(k), dict):
-            _deep_merge(dst[k], v)  # type: ignore[index]
-        else:
-            dst[k] = v
-
-
-# ===================== Core base classes =====================
-
-T_Feature = TypeVar("T_Feature", bound="BaseFeature")
-
-
-class BaseElement(BaseModel):
-    """
-    Base for Appliance/Feature:
-      - Declarative Defaults (inner class or mapping), values only
-      - Allowed-type enforcement at class creation (schema-time)
-      - Frozen instances
-    """
-    model_config = ConfigDict(
-        frozen=True,
-        extra="forbid",
-        validate_assignment=True,
-        protected_namespaces=(),  # allow names like __defaults_map__
-    )
-
-    __defaults_map__: Dict[str, Any] = {}
-
-    def __init_subclass__(cls, **kwargs):
-        super().__init_subclass__(**kwargs)
-
-        # 1) Collect Defaults (values) along MRO (base -> subclass)
-        merged: Dict[str, Any] = {}
-        for base in reversed(cls.mro()):  # parent first, subclass last (subclass wins)
-            spec = base.__dict__.get("Defaults")
-            if spec is None:
-                continue
-            if isinstance(spec, _DefaultsSpec):
-                flat = spec.mapping
-            elif isinstance(spec, type):
-                flat = _flatten_defaults_class(spec)
-            else:
-                continue
-            for k, v in flat.items():
-                _merge_path(merged, k, v)
-
-        # keep 'enabled' inside this map; we'll strip at validation time
-        cls.__defaults_map__ = merged
-
-        # 2) Schema-time allowed types for non-feature fields
-        is_appl = any(b.__name__ == "BaseAppliance" for b in cls.mro())
-        is_feat = any(b.__name__ == "BaseFeature" for b in cls.mro())
-        if is_appl or is_feat:
-            allowed = ALLOWED_APPLIANCE_FIELD_TYPES if is_appl else ALLOWED_FEATURE_FIELD_TYPES
-            for name, f in getattr(cls, "model_fields", {}).items():
-                ann = f.annotation
-                if ann is None:
-                    continue
-                if _is_feature_annotation(ann):
-                    continue  # feature fields checked in ApplianceMeta
-                if not _is_allowed_type(ann, allowed):
-                    kind = "Appliance" if is_appl else "Feature"
-                    raise TypeError(f"{kind} field '{cls.__name__}.{name}' has disallowed type: {ann}")
-
-    # >>> THIS MUST BE INSIDE THE CLASS <<<
-    @model_validator(mode="before")
-    @classmethod
-    def _apply_defaults_then_input(cls, values: Any):
-        if not isinstance(values, dict):
-            return values
-
-        # 1) seed from declared field defaults
-        merged: Dict[str, Any] = {}
-        for name, f in cls.model_fields.items():
-            if f.default is not None:
-                merged[name] = f.default
-            elif getattr(f, "default_factory", None) is not None:
-                merged[name] = f.default_factory()  # type: ignore[misc]
-
-        # 2) merge class Defaults (values only), then 3) user values
-        _deep_merge(merged, cls.__defaults_map__)
-        _deep_merge(merged, values)
-
-        # 3) per-feature handling
-        for name, f in cls.model_fields.items():
-            ann = f.annotation
-            base = get_args(ann)[0] if get_origin(ann) is Optional else ann
-            try:
-                if isinstance(base, type) and issubclass(base, BaseFeature):
-                    # user override flag?
-                    user_block = values.get(name) if isinstance(values, dict) else None
-                    user_enabled = None
-                    if isinstance(user_block, dict) and "enabled" in user_block:
-                        user_enabled = bool(user_block.get("enabled"))
-
-                    # class default flag?
-                    class_enabled = None
-                    defaults_block = cls.__defaults_map__.get(name) if isinstance(cls.__defaults_map__, dict) else None
-                    if isinstance(defaults_block, dict) and "enabled" in defaults_block:
-                        class_enabled = bool(defaults_block.get("enabled"))
-
-                    v = merged.get(name)
-
-                    # *** fallback: read flag from merged payload if still present ***
-                    merged_enabled = None
-                    if isinstance(v, dict) and "enabled" in v:
-                        merged_enabled = bool(v.get("enabled"))
-
-                    # final precedence: user > class > merged
-                    final_enabled = (
-                        user_enabled
-                        if user_enabled is not None
-                        else (class_enabled if class_enabled is not None else merged_enabled)
-                    )
-
-                    # strip any lingering 'enabled' key so the feature never sees it
-                    if isinstance(v, dict) and "enabled" in v:
-                        v = dict(v)
-                        v.pop("enabled", None)
-                        merged[name] = v
-
-                    if final_enabled is False:
-                        merged[name] = None
-                        continue
-
-                    # Merge feature defaults to ensure required fields are present
-                    feat_defaults = getattr(base, "__defaults_map__", {}) or {}
-                    if final_enabled is True and v is None:
-                        merged[name] = dict(feat_defaults)
-                    elif isinstance(v, dict):
-                        cfg: Dict[str, Any] = {}
-                        _deep_merge(cfg, feat_defaults)
-                        _deep_merge(cfg, v)
-                        merged[name] = cfg
-                    # If final_enabled is None and v is None → leave as None
-            except Exception:
-                pass
-
-        return merged
-
-
-class BaseFeature(BaseElement):
-    template_id: UUID4
-    template_short_name: StrictStr
-    template_long_name: Optional[StrictStr] = None
-    template_description: Optional[StrictStr] = None
-
-    @model_validator(mode="before")
-    @classmethod
-    def _strip_enabled_flag(cls, v: Any):
-        # Features never accept `enabled`; strip if present from Defaults or user input.
-        if isinstance(v, dict) and "enabled" in v:
-            v = dict(v)
-            v.pop("enabled", None)
-        return v
-
-
-class ApplianceMeta(ModelMetaclass):
-    def __new__(mcls, name, bases, namespace, **kwargs):
-        # Skip special handling for the abstract BaseAppliance itself
-        if name == 'BaseAppliance':
-            return super().__new__(mcls, name, bases, namespace, **kwargs)
-
-        # 1) Auto-inject feature fields from THIS class's inner `Features`
-        declared_here: Dict[str, type[BaseFeature]] = {}
-        inner = namespace.get("Features")
-        if isinstance(inner, type):
-            for fname, fval in vars(inner).items():
-                if fname.startswith("__"):
-                    continue
-                if isinstance(fval, type) and issubclass(fval, BaseFeature):
-                    declared_here[fname] = fval
-                    namespace.setdefault("__annotations__", {})
-                    if fname not in namespace["__annotations__"]:
-                        namespace["__annotations__"][fname] = Optional[fval]  # type: ignore[index]
-                        namespace[fname] = None  # default None; Defaults can enable/configure
-
-        # 2) Create the class via Pydantic's metaclass
-        cls = super().__new__(mcls, name, bases, namespace, **kwargs)
-
-        # 3) Discover current feature fields (after Pydantic processed annotations)
-        features_now: Dict[str, type[BaseFeature]] = {}
-        for field_name, f in cls.model_fields.items():
-            ann = f.annotation
-            base = get_args(ann)[0] if get_origin(ann) is Optional else ann
-            try:
-                if issubclass(base, BaseFeature):  # type: ignore[arg-type]
-                    features_now[field_name] = base  # type: ignore[assignment]
-            except Exception:
-                pass
-
-        # 4) Enforce parent schema monotonicity (no removal/type changes), allow additions
-        parent = next((b for b in cls.__mro__[1:] if isinstance(b, ApplianceMeta)), None)
-        parent_fields = dict(getattr(parent, "model_fields", {})) if parent else {}
-        parent_features = getattr(parent, "__feature_fields__", {}) if parent else {}
-
-        # PARENT FIELDS: present with identical annotation + same constraints (skip feature fields)
-        for pname, pfield in parent_fields.items():
-            if pname in parent_features:
-                continue
-            if pname not in cls.model_fields:
-                raise TypeError(f"{cls.__name__}: removing parent field '{pname}' is forbidden.")
-            child_field = cls.model_fields[pname]
-            if (not _annotation_equal(child_field.annotation, pfield.annotation)) or (tuple(child_field.metadata) != tuple(pfield.metadata)):
-                raise TypeError(f"{cls.__name__}: changing type/constraints of parent field '{pname}' is forbidden.")
-
-        # PARENT FEATURES: present with identical type
-        for fname, ftype in parent_features.items():
-            if fname not in features_now:
-                raise TypeError(f"{cls.__name__}: removing parent feature '{fname}' is forbidden.")
-            if features_now[fname] is not ftype:
-                raise TypeError(f"{cls.__name__}: retargeting feature '{fname}' is forbidden.")
-
-        # NEW FEATURES must be declared in THIS class's inner Features
-        new_feature_names = set(features_now) - set(parent_features)
-        if new_feature_names:
-            if not declared_here:
-                raise TypeError(
-                    f"{cls.__name__}: new features detected {sorted(new_feature_names)} "
-                    f"but none declared in this class's inner `Features`."
-                )
-            undeclared = [n for n in new_feature_names if n not in declared_here]
-            if undeclared:
-                raise TypeError(
-                    f"{cls.__name__}: new features {sorted(undeclared)} must be declared in this class's `Features`."
-                )
-
-        # 5) Publish the canonical sets
-        if parent and getattr(parent, "__declared_features__", {}):
-            merged_decl = dict(parent.__declared_features__)
-            merged_decl.update(declared_here)
-            cls.__declared_features__ = merged_decl
-        else:
-            cls.__declared_features__ = declared_here
-        cls.__feature_fields__ = features_now
-
-        return cls
-
-
-class BaseAppliance(BaseElement, Generic[T_Feature], metaclass=ApplianceMeta):
-    """
-    Feature binding is implicit via inner `class Features:`.
-    Subclasses may add fields and add features freely.
-    They may NOT change types of parent fields/features or remove them.
-    """
-    __declared_features__: Dict[str, type[BaseFeature]] = {}
-    __feature_fields__:    Dict[str, type[BaseFeature]] = {}
-
-    # core appliance schema
-    template_id: UUID4
-    template_short_name: StrictStr
-    template_long_name: Optional[StrictStr] = None
-    template_description: Optional[StrictStr] = None
-
-    cpu_cnt: StrictInt = Field(1, gt=0)
-    ram_size: ByteSize = Field(256, gt=128)
-    swap_size: ByteSize = Field(200, ge=0)
-    rootfs_size: ByteSize = Field(2048, ge=2048)
-
-    dabinst_id: UUID4 = Field(default_factory=uuid4)
-    dabinst_short_name: StrictStr
-    dabinst_long_name: Optional[StrictStr] = ""
-    dabinst_description: Optional[StrictStr] = ""
-    dabinst_creationdate: Optional[AwareDatetime] = Field(default_factory=lambda: _dt.now(tz=pytz.utc))

src/dabmodel/tools.py

@@ -0,0 +1,32 @@
+"""library's internal tools"""
+
+from uuid import UUID
+from datetime import datetime
+import json
+
+from frozendict import deepfreeze
+
+
+class LAMJSONEncoder(json.JSONEncoder):
+    """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)
+
+
+def LAMdeepfreeze(value):
+    """recursive freeze helper function"""
+    if isinstance(value, dict):
+        return deepfreeze(value)
+    if isinstance(value, set):
+        return frozenset(LAMdeepfreeze(v) for v in value)
+    if isinstance(value, list):
+        return tuple(LAMdeepfreeze(v) for v in value)
+    if isinstance(value, tuple):
+        return tuple(LAMdeepfreeze(v) for v in value)
+    return value