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import types |
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from collections import OrderedDict |
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from typing import Any, Dict, Callable, Tuple |
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from typish.classes._subscriptable_type import SubscriptableType |
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View Code Duplication |
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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from typish.functions._instance_of import instance_of |
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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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from typish.functions._subclass_of import subclass_of |
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from typish.functions._get_type_hints_of_callable import get_args_and_return_type |
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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 __hash__(self): |
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# This explicit super call is required for Python 3.5 and 3.6. |
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return super.__hash__(self) |
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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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View Code Duplication |
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 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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from typish.functions._get_type import get_type |
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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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