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""" |
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PRIVATE MODULE: do not import (from) it directly. |
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This module contains class implementations. |
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""" |
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import types |
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import warnings |
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from collections import OrderedDict |
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from typing import Any, Callable, Dict, Tuple |
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from typish._functions import ( |
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get_type, |
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subclass_of, |
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instance_of, |
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get_args_and_return_type, |
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) |
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class _SubscribedType(type): |
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""" |
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This class is a placeholder to let the IDE know the attributes of the |
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returned type after a __getitem__. |
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""" |
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__origin__ = None |
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__args__ = None |
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class SubscriptableType(type): |
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""" |
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This metaclass will allow a type to become subscriptable. |
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>>> class SomeType(metaclass=SubscriptableType): |
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... pass |
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>>> SomeTypeSub = SomeType['some args'] |
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>>> SomeTypeSub.__args__ |
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'some args' |
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>>> SomeTypeSub.__origin__.__name__ |
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'SomeType' |
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""" |
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def __init_subclass__(mcs, **kwargs): |
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mcs._hash = None |
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mcs.__args__ = None |
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mcs.__origin__ = None |
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def __getitem__(self, item) -> _SubscribedType: |
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body = { |
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**self.__dict__, |
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'__args__': item, |
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'__origin__': self, |
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} |
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bases = self, *self.__bases__ |
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result = type(self.__name__, bases, body) |
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if hasattr(result, '_after_subscription'): |
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# TODO check if _after_subscription is static |
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result._after_subscription(item) |
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return result |
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def __eq__(self, other): |
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self_args = getattr(self, '__args__', None) |
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self_origin = getattr(self, '__origin__', None) |
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other_args = getattr(other, '__args__', None) |
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other_origin = getattr(other, '__origin__', None) |
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return self_args == other_args and self_origin == other_origin |
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def __hash__(self): |
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if not self._hash: |
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self._hash = hash('{}{}'.format(self.__origin__, self.__args__)) |
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return self._hash |
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class _SomethingMeta(SubscriptableType): |
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""" |
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This metaclass is coupled to ``Interface``. |
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""" |
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def __instancecheck__(self, instance: object) -> bool: |
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# Check if all attributes from self.signature are also present in |
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# instance and also check that their types correspond. |
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sig = self.signature() |
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for key in sig: |
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attr = getattr(instance, key, None) |
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if not attr or not instance_of(attr, sig[key]): |
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return False |
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return True |
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def __subclasscheck__(self, subclass: type) -> bool: |
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# If an instance of type subclass is an instance of self, then subclass |
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# is a sub class of self. |
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self_sig = self.signature() |
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other_sig = Something.like(subclass).signature() |
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for attr in self_sig: |
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if attr in other_sig: |
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attr_sig = other_sig[attr] |
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if (not isinstance(subclass.__dict__[attr], staticmethod) |
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and not isinstance(subclass.__dict__[attr], classmethod) |
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and subclass_of(attr_sig, Callable)): |
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# The attr must be a regular method or class method, so the |
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# first parameter should be ignored. |
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args, rt = get_args_and_return_type(attr_sig) |
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attr_sig = Callable[list(args[1:]), rt] |
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if not subclass_of(attr_sig, self_sig[attr]): |
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return False |
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return True |
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def __eq__(self, other: 'Something') -> bool: |
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return (isinstance(other, _SomethingMeta) |
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and self.signature() == other.signature()) |
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def __repr__(self): |
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sig = self.signature() |
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sig_ = ', '.join(["'{}': {}".format(k, self._type_repr(sig[k])) |
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for k in sig]) |
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return 'typish.Something[{}]'.format(sig_) |
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def _type_repr(self, obj): |
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"""Return the repr() of an object, special-casing types (internal helper). |
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If obj is a type, we return a shorter version than the default |
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type.__repr__, based on the module and qualified name, which is |
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typically enough to uniquely identify a type. For everything |
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else, we fall back on repr(obj). |
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""" |
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if isinstance(obj, type) and not issubclass(obj, Callable): |
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if obj.__module__ == 'builtins': |
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return obj.__qualname__ |
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return '{}.{}'.format(obj.__module__, obj.__qualname__) |
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if obj is ...: |
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return '...' |
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if isinstance(obj, types.FunctionType): |
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return obj.__name__ |
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return repr(obj) |
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class Something(type, metaclass=_SomethingMeta): |
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""" |
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This class allows one to define an interface for something that has some |
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attributes, such as objects or classes or maybe even modules. |
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""" |
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@classmethod |
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def signature(mcs) -> Dict[str, type]: |
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""" |
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Return the signature of this ``Something`` as a dict. |
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:return: a dict with attribute names as keys and types as values. |
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""" |
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result = OrderedDict() |
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args = mcs.__args__ |
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if isinstance(mcs.__args__, slice): |
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args = (mcs.__args__,) |
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arg_keys = sorted(args) |
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if isinstance(mcs.__args__, dict): |
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for key in arg_keys: |
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result[key] = mcs.__args__[key] |
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else: |
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for slice_ in arg_keys: |
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result[slice_.start] = slice_.stop |
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return result |
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def __getattr__(cls, item): |
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# This method exists solely to fool the IDE into believing that |
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# Something can have any attribute. |
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return type.__getattr__(cls, item) |
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@staticmethod |
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def of(obj: Any, exclude_privates: bool = True) -> 'Something': |
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warnings.warn('Something.of is deprecated and will be removed in the ' |
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'next minor release. Use Something.like instead.', |
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category=DeprecationWarning, stacklevel=2) |
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return Something.like(obj, exclude_privates) |
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@staticmethod |
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def like(obj: Any, exclude_privates: bool = True) -> 'Something': |
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""" |
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Return a ``Something`` for the given ``obj``. |
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:param obj: the object of which a ``Something`` is to be made. |
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:param exclude_privates: if ``True``, private variables are excluded. |
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:return: a ``Something`` that corresponds to ``obj``. |
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""" |
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signature = {attr: get_type(getattr(obj, attr)) for attr in dir(obj) |
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if not exclude_privates or not attr.startswith('_')} |
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return Something[signature] |
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TypingType = Something['__origin__': type, '__args__': Tuple[type, ...]] |
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ramonhagenaars /
typish
