codekingpro/portable-devtools

1"""2meta.py3 4Some useful metaclasses.5"""6 7from __future__ import annotations8 9from typing import TYPE_CHECKING10 11if TYPE_CHECKING:12    from typing import Any13 14 15class LeafClassesMeta(type):16    """17    A metaclass for classes that keeps track of all of them that18    aren't base classes.19 20    >>> Parent = LeafClassesMeta('MyParentClass', (), {})21    >>> Parent in Parent._leaf_classes22    True23    >>> Child = LeafClassesMeta('MyChildClass', (Parent,), {})24    >>> Child in Parent._leaf_classes25    True26    >>> Parent in Parent._leaf_classes27    False28 29    >>> Other = LeafClassesMeta('OtherClass', (), {})30    >>> Parent in Other._leaf_classes31    False32    >>> len(Other._leaf_classes)33    134    """35 36    _leaf_classes: set[type[Any]]37 38    def __init__(39        cls,40        name: str,41        bases: tuple[type[object], ...],42        attrs: dict[str, object],43    ) -> None:44        if not hasattr(cls, '_leaf_classes'):45            cls._leaf_classes = set()46        leaf_classes = getattr(cls, '_leaf_classes')47        leaf_classes.add(cls)48        # remove any base classes49        leaf_classes -= set(bases)50 51 52class TagRegistered(type):53    """54    As classes of this metaclass are created, they keep a registry in the55    base class of all classes by a class attribute, indicated by attr_name.56 57    >>> FooObject = TagRegistered('FooObject', (), dict(tag='foo'))58    >>> FooObject._registry['foo'] is FooObject59    True60    >>> BarObject = TagRegistered('Barobject', (FooObject,), dict(tag='bar'))61    >>> FooObject._registry is BarObject._registry62    True63    >>> len(FooObject._registry)64    265 66    '...' below should be 'jaraco.classes' but for pytest-dev/pytest#339667    >>> FooObject._registry['bar']68    <class '....meta.Barobject'>69    """70 71    attr_name = 'tag'72 73    def __init__(74        cls,75        name: str,76        bases: tuple[type[object], ...],77        namespace: dict[str, object],78    ) -> None:79        super(TagRegistered, cls).__init__(name, bases, namespace)80        if not hasattr(cls, '_registry'):81            cls._registry = {}82        meta = cls.__class__83        attr = getattr(cls, meta.attr_name, None)84        if attr:85            cls._registry[attr] = cls86