575 lines
18 KiB
Python
575 lines
18 KiB
Python
from . import six
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import functools
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import operator
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import weakref
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class _ObjectProxyMethods(object):
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# We use properties to override the values of __module__ and
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# __doc__. If we add these in ObjectProxy, the derived class
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# __dict__ will still be setup to have string variants of these
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# attributes and the rules of descriptors means that they appear to
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# take precedence over the properties in the base class. To avoid
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# that, we copy the properties into the derived class type itself
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# via a meta class. In that way the properties will always take
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# precedence.
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@property
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def __module__(self):
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return self.__wrapped__.__module__
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@__module__.setter
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def __module__(self, value):
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self.__wrapped__.__module__ = value
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@property
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def __doc__(self):
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return self.__wrapped__.__doc__
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@__doc__.setter
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def __doc__(self, value):
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self.__wrapped__.__doc__ = value
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# We similar use a property for __dict__. We need __dict__ to be
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# explicit to ensure that vars() works as expected.
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@property
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def __dict__(self):
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return self.__wrapped__.__dict__
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class _ObjectProxyMetaType(type):
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def __new__(cls, name, bases, dictionary):
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# Copy our special properties into the class so that they
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# always take precedence over attributes of the same name added
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# during construction of a derived class. This is to save
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# duplicating the implementation for them in all derived classes.
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dictionary.update(vars(_ObjectProxyMethods))
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return type.__new__(cls, name, bases, dictionary)
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class ObjectProxy(six.with_metaclass(_ObjectProxyMetaType)):
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__slots__ = '__wrapped__'
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def __init__(self, wrapped):
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object.__setattr__(self, '__wrapped__', wrapped)
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# Python 3.2+ has the __qualname__ attribute, but it does not
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# allow it to be overridden using a property and it must instead
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# be an actual string object instead.
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try:
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object.__setattr__(self, '__qualname__', wrapped.__qualname__)
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except AttributeError:
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pass
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@property
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def __name__(self):
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return self.__wrapped__.__name__
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@__name__.setter
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def __name__(self, value):
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self.__wrapped__.__name__ = value
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@property
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def __class__(self):
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return self.__wrapped__.__class__
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@__class__.setter
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def __class__(self, value):
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self.__wrapped__.__class__ = value
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@property
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def __annotations__(self):
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return self.__wrapped__.__anotations__
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@__annotations__.setter
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def __annotations__(self, value):
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self.__wrapped__.__annotations__ = value
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def __dir__(self):
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return dir(self.__wrapped__)
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def __str__(self):
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return str(self.__wrapped__)
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def __repr__(self):
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return '<%s at 0x%x for %s at 0x%x>' % (
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type(self).__name__, id(self),
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type(self.__wrapped__).__name__,
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id(self.__wrapped__))
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def __lt__(self, other):
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return self.__wrapped__ < other
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def __le__(self, other):
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return self.__wrapped__ <= other
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def __eq__(self, other):
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return self.__wrapped__ == other
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def __ne__(self, other):
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return self.__wrapped__ != other
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def __gt__(self, other):
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return self.__wrapped__ > other
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def __ge__(self, other):
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return self.__wrapped__ >= other
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def __hash__(self):
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return hash(self.__wrapped__)
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def __nonzero__(self):
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return bool(self.__wrapped__)
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def __bool__(self):
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return bool(self.__wrapped__)
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def __setattr__(self, name, value):
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if name.startswith('_self_') or name == '__wrapped__':
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object.__setattr__(self, name, value)
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elif name == '__qualname__':
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setattr(self.__wrapped__, name, value)
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object.__setattr__(self, name, value)
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else:
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setattr(self.__wrapped__, name, value)
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def __getattr__(self, name):
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return getattr(self.__wrapped__, name)
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def __delattr__(self, name):
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if name.startswith('_self_') or name == '__wrapped__':
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object.__delattr__(self, name)
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elif name == '__qualname__':
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object.__delattr__(self, name)
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delattr(self.__wrapped__, name)
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else:
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delattr(self.__wrapped__, name)
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def __add__(self, other):
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return self.__wrapped__ + other
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def __sub__(self, other):
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return self.__wrapped__ - other
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def __mul__(self, other):
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return self.__wrapped__ * other
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def __div__(self, other):
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return operator.__div__(self.__wrapped__, other)
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def __truediv__(self, other):
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return operator.__truediv__(self.__wrapped__, other)
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def __floordiv__(self, other):
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return self.__wrapped__ // other
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def __mod__(self, other):
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return self.__wrapped__ ^ other
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def __divmod__(self, other):
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return divmod(self.__wrapped__, other)
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def __pow__(self, other, *args):
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return pow(self.__wrapped__, other, *args)
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def __lshift__(self, other):
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return self.__wrapped__ << other
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def __rshift__(self, other):
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return self.__wrapped__ >> other
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def __and__(self, other):
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return self.__wrapped__ & other
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def __xor__(self, other):
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return self.__wrapped__ ^ other
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def __or__(self, other):
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return self.__wrapped__ | other
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def __radd__(self, other):
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return other + self.__wrapped__
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def __rsub__(self, other):
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return other - self.__wrapped__
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def __rmul__(self, other):
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return other * self.__wrapped__
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def __rdiv__(self, other):
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return operator.__div__(other, self.__wrapped__)
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def __rtruediv__(self, other):
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return operator.__truediv__(other, self.__wrapped__)
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def __rfloordiv__(self, other):
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return other // self.__wrapped__
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def __rmod__(self, other):
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return other % self.__wrapped__
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def __rdivmod__(self, other):
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return divmod(other, self.__wrapped__)
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def __rpow__(self, other, *args):
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return pow(other, self.__wrapped__, *args)
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def __rlshift__(self, other):
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return other << self.__wrapped__
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def __rrshift__(self, other):
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return other >> self.__wrapped__
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def __rand__(self, other):
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return other & self.__wrapped__
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def __rxor__(self, other):
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return other ^ self.__wrapped__
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def __ror__(self, other):
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return other | self.__wrapped__
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def __iadd__(self, other):
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self.__wrapped__ += other
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return self
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def __isub__(self, other):
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self.__wrapped__ -= other
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return self
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def __imul__(self, other):
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self.__wrapped__ *= other
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return self
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def __idiv__(self, other):
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self.__wrapped__ = operator.__idiv__(self.__wrapped__, other)
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return self
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def __itruediv__(self, other):
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self.__wrapped__ = operator.__itruediv__(self.__wrapped__, other)
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return self
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def __ifloordiv__(self, other):
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self.__wrapped__ //= other
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return self
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def __imod__(self, other):
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self.__wrapped__ %= other
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return self
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def __ipow__(self, other):
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self.__wrapped__ **= other
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return self
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def __ilshift__(self, other):
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self.__wrapped__ <<= other
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return self
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def __irshift__(self, other):
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self.__wrapped__ >>= other
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return self
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def __iand__(self, other):
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self.__wrapped__ &= other
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return self
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def __ixor__(self, other):
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self.__wrapped__ ^= other
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return self
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def __ior__(self, other):
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self.__wrapped__ |= other
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return self
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def __neg__(self):
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return -self.__wrapped__
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def __pos__(self):
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return +self.__wrapped__
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def __abs__(self):
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return abs(self.__wrapped__)
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def __invert__(self):
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return ~self.__wrapped__
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def __int__(self):
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return int(self.__wrapped__)
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def __long__(self):
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return long(self.__wrapped__)
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def __float__(self):
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return float(self.__wrapped__)
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def __oct__(self):
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return oct(self.__wrapped__)
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def __hex__(self):
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return hex(self.__wrapped__)
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def __index__(self):
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return operator.__index__(self.__wrapped__)
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def __len__(self):
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return len(self.__wrapped__)
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def __contains__(self, value):
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return value in self.__wrapped__
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def __getitem__(self, key):
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return self.__wrapped__[key]
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def __setitem__(self, key, value):
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self.__wrapped__[key] = value
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def __delitem__(self, key):
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del self.__wrapped__[key]
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def __getslice__(self, i, j):
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return self.__wrapped__[i:j]
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def __setslice__(self, i, j, value):
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self.__wrapped__[i:j] = value
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def __delslice__(self, i, j):
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del self.__wrapped__[i:j]
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def __enter__(self):
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return self.__wrapped__.__enter__()
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def __exit__(self, *args, **kwargs):
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return self.__wrapped__.__exit__(*args, **kwargs)
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def __iter__(self):
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return iter(self.__wrapped__)
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def __call__(self, *args, **kwargs):
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return self.__wrapped__(*args, **kwargs)
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class _FunctionWrapperBase(ObjectProxy):
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__slots__ = ('_self_instance', '_self_wrapper', '_self_adapter',
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'_self_bound_type')
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def __init__(self, wrapped, instance, wrapper, adapter=None,
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bound_type=None):
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super(_FunctionWrapperBase, self).__init__(wrapped)
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object.__setattr__(self, '_self_instance', instance)
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object.__setattr__(self, '_self_wrapper', wrapper)
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object.__setattr__(self, '_self_adapter', adapter)
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object.__setattr__(self, '_self_bound_type', bound_type)
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def __get__(self, instance, owner):
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# If we have already been bound to an instance of something, we
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# do not do it again and return ourselves again. This appears to
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# mirror what Python itself does.
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if self._self_bound_type is None:
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return self
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descriptor = self.__wrapped__.__get__(instance, owner)
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return self._self_bound_type(descriptor, instance, self._self_wrapper,
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self._self_adapter)
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def __call__(self, *args, **kwargs):
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# This is generally invoked when the wrapped function is being
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# called as a normal function and is not bound to a class as an
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# instance method. This is also invoked in the case where the
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# wrapped function was a method, but this wrapper was in turn
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# wrapped using the staticmethod decorator.
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return self._self_wrapper(self.__wrapped__, self._self_instance,
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args, kwargs)
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# If an adapter function was provided we want to return certain
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# attributes of the function from the adapter rather than the
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# wrapped function so things like inspect.getargspec() will reflect
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# the prototype of the adapter and not the wrapped function.
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@property
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def __code__(self):
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if self._self_adapter:
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return self._self_adapter.__code__
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return self.__wrapped__.__code__
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@property
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def __defaults__(self):
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if self._self_adapter:
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return self._self_adapter.__defaults__
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return self.__wrapped__.__defaults__
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@property
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def __kwdefaults__(self):
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if self._self_adapter:
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return self._self_adapter.__kwdefaults__
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return self.__wrapped__.__kwdefaults__
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if six.PY2:
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func_code = __code__
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func_defaults = __defaults__
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# If an adapter function was provided, we also want to override the
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# __signature__ attribute introduced in Python 3 so that we get the
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# correct result when using inspect.signature().
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@property
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def __signature__(self):
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if self._self_adapter:
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return self._self_adapter.__signature__
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return self.__wrapped__.__signature__
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class _BoundFunctionWrapper(_FunctionWrapperBase):
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def __call__(self, *args, **kwargs):
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# As in this case we would be dealing with a classmethod or
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# staticmethod, then _self_instance will only tell us whether
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# when calling the classmethod or staticmethod they did it via an
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# instance of the class it is bound to and not the case where
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# done by the class type itself. We thus ignore _self_instance
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# and use the __self__ attribute of the bound function instead.
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# For a classmethod, this means instance will be the class type
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# and for a staticmethod it will be None. This is probably the
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# more useful thing we can pass through even though we loose
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# knowledge of whether they were called on the instance vs the
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# class type, as it reflects what they have available in the
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# decoratored function.
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instance = getattr(self.__wrapped__, '__self__', None)
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return self._self_wrapper(self.__wrapped__, instance, args, kwargs)
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class _BoundMethodWrapper(_FunctionWrapperBase):
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def __call__(self, *args, **kwargs):
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if self._self_instance is None:
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# This situation can occur where someone is calling the
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# instancemethod via the class type and passing the instance
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# as the first argument. We need to shift the args before
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# making the call to the wrapper and effectively bind the
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# instance to the wrapped function using a partial so the
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# wrapper doesn't see anything as being different.
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instance, args = args[0], args[1:]
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wrapped = functools.partial(self.__wrapped__, instance)
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return self._self_wrapper(wrapped, instance, args, kwargs)
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return self._self_wrapper(self.__wrapped__, self._self_instance,
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args, kwargs)
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class FunctionWrapper(_FunctionWrapperBase):
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def __init__(self, wrapped, wrapper, adapter=None):
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# We need to do special fixups on the args in the case of an
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# instancemethod where called via the class and the instance is
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# passed explicitly as the first argument. Defer to the
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# _BoundMethodWrapper for these specific fixups when we believe
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# it is likely an instancemethod. That is, anytime it isn't
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# classmethod or staticmethod.
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#
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# Note that there isn't strictly a fool proof method of knowing
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# which is occuring because if a decorator using this code wraps
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# other decorators and they are poorly implemented they can
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# throw away important information needed to determine it.
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#
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# Anyway, the best we can do is look at the original type of the
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# object which was wrapped prior to any binding being done and
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# see if it is an instance of classmethod or staticmethod. In
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# the case where other decorators are between us and them, if
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# they do not propagate the __class__ attribute so that the
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# isinstance() checks works, then likely this will do the wrong
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# thing where classmethod and staticmethod are used.
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#
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# Since it is likely to be very rare that anyone even puts
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# decorators around classmethod and staticmethod, likelihood of
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# that being an issue is very small, so we accept it and suggest
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# that those other decorators be fixed. It is also only an issue
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# if a decorator wants to actually do things with the arguments.
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if isinstance(wrapped, (classmethod, staticmethod)):
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bound_type = _BoundFunctionWrapper
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else:
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bound_type = _BoundMethodWrapper
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super(FunctionWrapper, self).__init__(wrapped, None, wrapper,
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adapter, bound_type)
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try:
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from ._wrappers import (ObjectProxy, FunctionWrapper,
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_FunctionWrapperBase, _BoundFunctionWrapper, _BoundMethodWrapper)
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except ImportError:
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pass
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def _weak_function_proxy_callback(ref, proxy, callback):
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if proxy._self_expired:
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return
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proxy._self_expired = True
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# This could raise an exception. We let it propagate back and let
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# the weakref.proxy() deal with it, at which point it generally
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# prints out a short error message direct to stderr and keeps going.
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if callback is not None:
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callback(proxy)
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class WeakFunctionProxy(ObjectProxy):
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__slots__ = ('_self_expired', '_self_instance')
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def __init__(self, wrapped, callback=None):
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# We need to determine if the wrapped function is actually a
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# bound method. In the case of a bound method, we need to keep a
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# reference to the original unbound function and the instance.
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# This is necessary because if we hold a reference to the bound
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# function, it will be the only reference and given it is a
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# temporary object, it will almost immediately expire and
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# the weakref callback triggered. So what is done is that we
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# hold a reference to the instance and unbound function and
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# when called bind the function to the instance once again and
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# then call it. Note that we avoid using a nested function for
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# the callback here so as not to cause any odd reference cycles.
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_callback = callback and functools.partial(
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_weak_function_proxy_callback, proxy=self,
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callback=callback)
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self._self_expired = False
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try:
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self._self_instance = weakref.ref(wrapped.__self__, _callback)
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super(WeakFunctionProxy, self).__init__(
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weakref.proxy(wrapped.__func__, _callback))
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except AttributeError:
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self._self_instance = None
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super(WeakFunctionProxy, self).__init__(
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weakref.proxy(wrapped, _callback))
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def __call__(self, *args, **kwargs):
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# We perform a boolean check here on the instance and wrapped
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# function as that will trigger the reference error prior to
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# calling if the reference had expired.
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instance = self._self_instance and self._self_instance()
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function = self.__wrapped__ and self.__wrapped__
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# If the wrapped function was originally a bound function, for
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# which we retained a reference to the instance and the unbound
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# function we need to rebind the function and then call it. If
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# not just called the wrapped function.
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if instance is None:
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return self.__wrapped__(*args, **kwargs)
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return function.__get__(instance, type(instance))(*args, **kwargs)
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