900 lines
32 KiB
Python
900 lines
32 KiB
Python
import sys
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import functools
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import operator
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import weakref
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import inspect
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PY2 = sys.version_info[0] == 2
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PY3 = sys.version_info[0] == 3
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if PY3:
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string_types = str,
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else:
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string_types = basestring,
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def with_metaclass(meta, *bases):
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"""Create a base class with a metaclass."""
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return meta("NewBase", bases, {})
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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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# Need to also propagate the special __weakref__ attribute for case
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# where decorating classes which will define this. If do not define
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# it and use a function like inspect.getmembers() on a decorator
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# class it will fail. This can't be in the derived classes.
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@property
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def __weakref__(self):
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return self.__wrapped__.__weakref__
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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(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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if PY3:
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def __bytes__(self):
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return bytes(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 __reversed__(self):
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return reversed(self.__wrapped__)
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if PY3:
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def __round__(self):
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return round(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_'):
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object.__setattr__(self, name, value)
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elif name == '__wrapped__':
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object.__setattr__(self, name, value)
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try:
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object.__delattr__(self, '__qualname__')
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except AttributeError:
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pass
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try:
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object.__setattr__(self, '__qualname__', value.__qualname__)
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except AttributeError:
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pass
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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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elif hasattr(type(self), name):
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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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# If we are being to lookup '__wrapped__' then the
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# '__init__()' method cannot have been called.
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if name == '__wrapped__':
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raise ValueError('wrapper has not been initialised')
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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_'):
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object.__delattr__(self, name)
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elif name == '__wrapped__':
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raise TypeError('__wrapped__ must be an object')
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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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elif hasattr(type(self), name):
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object.__delattr__(self, 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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class CallableObjectProxy(ObjectProxy):
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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_enabled',
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'_self_binding', '_self_parent')
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def __init__(self, wrapped, instance, wrapper, enabled=None,
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binding='function', parent=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_enabled', enabled)
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object.__setattr__(self, '_self_binding', binding)
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object.__setattr__(self, '_self_parent', parent)
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def __get__(self, instance, owner):
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# This method is actually doing double duty for both unbound and
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# bound derived wrapper classes. It should possibly be broken up
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# and the distinct functionality moved into the derived classes.
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# Can't do that straight away due to some legacy code which is
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# relying on it being here in this base class.
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#
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# The distinguishing attribute which determines whether we are
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# being called in an unbound or bound wrapper is the parent
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# attribute. If binding has never occured, then the parent will
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# be None.
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#
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# First therefore, is if we are called in an unbound wrapper. In
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# this case we perform the binding.
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#
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# We have one special case to worry about here. This is where we
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# are decorating a nested class. In this case the wrapped class
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# would not have a __get__() method to call. In that case we
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# simply return self.
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#
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# Note that we otherwise still do binding even if instance is
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# None and accessing an unbound instance method from a class.
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# This is because we need to be able to later detect that
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# specific case as we will need to extract the instance from the
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# first argument of those passed in.
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if self._self_parent is None:
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if not inspect.isclass(self.__wrapped__):
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descriptor = self.__wrapped__.__get__(instance, owner)
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return self.__bound_function_wrapper__(descriptor, instance,
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self._self_wrapper, self._self_enabled,
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self._self_binding, self)
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return self
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# Now we have the case of binding occuring a second time on what
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# was already a bound function. In this case we would usually
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# return ourselves again. This mirrors what Python does.
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#
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# The special case this time is where we were originally bound
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# with an instance of None and we were likely an instance
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# method. In that case we rebind against the original wrapped
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# function from the parent again.
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if self._self_instance is None and self._self_binding == 'function':
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descriptor = self._self_parent.__wrapped__.__get__(
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instance, owner)
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return self._self_parent.__bound_function_wrapper__(
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descriptor, instance, self._self_wrapper,
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self._self_enabled, self._self_binding,
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self._self_parent)
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return self
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def __call__(self, *args, **kwargs):
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# If enabled has been specified, then evaluate it at this point
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# and if the wrapper is not to be executed, then simply return
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# the bound function rather than a bound wrapper for the bound
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# function. When evaluating enabled, if it is callable we call
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# it, otherwise we evaluate it as a boolean.
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if self._self_enabled is not None:
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if callable(self._self_enabled):
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if not self._self_enabled():
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return self.__wrapped__(*args, **kwargs)
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elif not self._self_enabled:
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return self.__wrapped__(*args, **kwargs)
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# This can occur where initial function wrapper was applied to
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# a function that was already bound to an instance. In that case
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# we want to extract the instance from the function and use it.
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if self._self_binding == 'function':
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if self._self_instance is None:
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instance = getattr(self.__wrapped__, '__self__', None)
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if instance is not None:
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return self._self_wrapper(self.__wrapped__, instance,
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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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class BoundFunctionWrapper(_FunctionWrapperBase):
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def __call__(self, *args, **kwargs):
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# If enabled has been specified, then evaluate it at this point
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# and if the wrapper is not to be executed, then simply return
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# the bound function rather than a bound wrapper for the bound
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# function. When evaluating enabled, if it is callable we call
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# it, otherwise we evaluate it as a boolean.
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if self._self_enabled is not None:
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if callable(self._self_enabled):
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if not self._self_enabled():
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return self.__wrapped__(*args, **kwargs)
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elif not self._self_enabled:
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return self.__wrapped__(*args, **kwargs)
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# We need to do things different depending on whether we are
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# likely wrapping an instance method vs a static method or class
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# method.
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if self._self_binding == 'function':
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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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if not args:
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raise TypeError('missing 1 required positional argument')
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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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else:
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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.
|
|
# For a classmethod, this means instance will be the class type
|
|
# and for a staticmethod it will be None. This is probably the
|
|
# more useful thing we can pass through even though we loose
|
|
# knowledge of whether they were called on the instance vs the
|
|
# class type, as it reflects what they have available in the
|
|
# decoratored function.
|
|
|
|
instance = getattr(self.__wrapped__, '__self__', None)
|
|
|
|
return self._self_wrapper(self.__wrapped__, instance, args,
|
|
kwargs)
|
|
|
|
class FunctionWrapper(_FunctionWrapperBase):
|
|
|
|
__bound_function_wrapper__ = BoundFunctionWrapper
|
|
|
|
def __init__(self, wrapped, wrapper, enabled=None):
|
|
# What it is we are wrapping here could be anything. We need to
|
|
# try and detect specific cases though. In particular, we need
|
|
# to detect when we are given something that is a method of a
|
|
# class. Further, we need to know when it is likely an instance
|
|
# method, as opposed to a class or static method. This can
|
|
# become problematic though as there isn't strictly a fool proof
|
|
# method of knowing.
|
|
#
|
|
# The situations we could encounter when wrapping a method are:
|
|
#
|
|
# 1. The wrapper is being applied as part of a decorator which
|
|
# is a part of the class definition. In this case what we are
|
|
# given is the raw unbound function, classmethod or staticmethod
|
|
# wrapper objects.
|
|
#
|
|
# The problem here is that we will not know we are being applied
|
|
# in the context of the class being set up. This becomes
|
|
# important later for the case of an instance method, because in
|
|
# that case we just see it as a raw function and can't
|
|
# distinguish it from wrapping a normal function outside of
|
|
# a class context.
|
|
#
|
|
# 2. The wrapper is being applied when performing monkey
|
|
# patching of the class type afterwards and the method to be
|
|
# wrapped was retrieved direct from the __dict__ of the class
|
|
# type. This is effectively the same as (1) above.
|
|
#
|
|
# 3. The wrapper is being applied when performing monkey
|
|
# patching of the class type afterwards and the method to be
|
|
# wrapped was retrieved from the class type. In this case
|
|
# binding will have been performed where the instance against
|
|
# which the method is bound will be None at that point.
|
|
#
|
|
# This case is a problem because we can no longer tell if the
|
|
# method was a static method, plus if using Python3, we cannot
|
|
# tell if it was an instance method as the concept of an
|
|
# unnbound method no longer exists.
|
|
#
|
|
# 4. The wrapper is being applied when performing monkey
|
|
# patching of an instance of a class. In this case binding will
|
|
# have been perfomed where the instance was not None.
|
|
#
|
|
# This case is a problem because we can no longer tell if the
|
|
# method was a static method.
|
|
#
|
|
# Overall, the best we can do is look at the original type of the
|
|
# object which was wrapped prior to any binding being done and
|
|
# see if it is an instance of classmethod or staticmethod. In
|
|
# the case where other decorators are between us and them, if
|
|
# they do not propagate the __class__ attribute so that the
|
|
# isinstance() checks works, then likely this will do the wrong
|
|
# thing where classmethod and staticmethod are used.
|
|
#
|
|
# Since it is likely to be very rare that anyone even puts
|
|
# decorators around classmethod and staticmethod, likelihood of
|
|
# that being an issue is very small, so we accept it and suggest
|
|
# that those other decorators be fixed. It is also only an issue
|
|
# if a decorator wants to actually do things with the arguments.
|
|
#
|
|
# As to not being able to identify static methods properly, we
|
|
# just hope that that isn't something people are going to want
|
|
# to wrap, or if they do suggest they do it the correct way by
|
|
# ensuring that it is decorated in the class definition itself,
|
|
# or patch it in the __dict__ of the class type.
|
|
#
|
|
# So to get the best outcome we can, whenever we aren't sure what
|
|
# it is, we label it as a 'function'. If it was already bound and
|
|
# that is rebound later, we assume that it will be an instance
|
|
# method and try an cope with the possibility that the 'self'
|
|
# argument it being passed as an explicit argument and shuffle
|
|
# the arguments around to extract 'self' for use as the instance.
|
|
|
|
if isinstance(wrapped, classmethod):
|
|
binding = 'classmethod'
|
|
|
|
elif isinstance(wrapped, staticmethod):
|
|
binding = 'staticmethod'
|
|
|
|
elif hasattr(wrapped, '__self__'):
|
|
if inspect.isclass(wrapped.__self__):
|
|
binding = 'classmethod'
|
|
else:
|
|
binding = 'function'
|
|
|
|
else:
|
|
binding = 'function'
|
|
|
|
super(FunctionWrapper, self).__init__(wrapped, None, wrapper,
|
|
enabled, binding)
|
|
|
|
try:
|
|
from ._wrappers import (ObjectProxy, CallableObjectProxy, FunctionWrapper,
|
|
BoundFunctionWrapper, _FunctionWrapperBase)
|
|
except ImportError:
|
|
pass
|
|
|
|
# Helper functions for applying wrappers to existing functions.
|
|
|
|
def resolve_path(module, name):
|
|
if isinstance(module, string_types):
|
|
__import__(module)
|
|
module = sys.modules[module]
|
|
|
|
parent = module
|
|
|
|
path = name.split('.')
|
|
attribute = path[0]
|
|
|
|
original = getattr(parent, attribute)
|
|
for attribute in path[1:]:
|
|
parent = original
|
|
|
|
# We can't just always use getattr() because in doing
|
|
# that on a class it will cause binding to occur which
|
|
# will complicate things later and cause some things not
|
|
# to work. For the case of a class we therefore access
|
|
# the __dict__ directly. To cope though with the wrong
|
|
# class being given to us, or a method being moved into
|
|
# a base class, we need to walk the class heirarchy to
|
|
# work out exactly which __dict__ the method was defined
|
|
# in, as accessing it from __dict__ will fail if it was
|
|
# not actually on the class given. Fallback to using
|
|
# getattr() if we can't find it. If it truly doesn't
|
|
# exist, then that will fail.
|
|
|
|
if inspect.isclass(original):
|
|
for cls in inspect.getmro(original):
|
|
if attribute in vars(original):
|
|
original = vars(original)[attribute]
|
|
break
|
|
else:
|
|
original = getattr(original, attribute)
|
|
|
|
else:
|
|
original = getattr(original, attribute)
|
|
|
|
return (parent, attribute, original)
|
|
|
|
def apply_patch(parent, attribute, replacement):
|
|
setattr(parent, attribute, replacement)
|
|
|
|
def wrap_object(module, name, factory, args=(), kwargs={}):
|
|
(parent, attribute, original) = resolve_path(module, name)
|
|
wrapper = factory(original, *args, **kwargs)
|
|
apply_patch(parent, attribute, wrapper)
|
|
return wrapper
|
|
|
|
# Function for applying a proxy object to an attribute of a class
|
|
# instance. The wrapper works by defining an attribute of the same name
|
|
# on the class which is a descriptor and which intercepts access to the
|
|
# instance attribute. Note that this cannot be used on attributes which
|
|
# are themselves defined by a property object.
|
|
|
|
class AttributeWrapper(object):
|
|
|
|
def __init__(self, attribute, factory, args, kwargs):
|
|
self.attribute = attribute
|
|
self.factory = factory
|
|
self.args = args
|
|
self.kwargs = kwargs
|
|
|
|
def __get__(self, instance, owner):
|
|
value = instance.__dict__[self.attribute]
|
|
return self.factory(value, *self.args, **self.kwargs)
|
|
|
|
def __set__(self, instance, value):
|
|
instance.__dict__[self.attribute] = value
|
|
|
|
def __delete__(self, instance):
|
|
del instance.__dict__[self.attribute]
|
|
|
|
def wrap_object_attribute(module, name, factory, args=(), kwargs={}):
|
|
path, attribute = name.rsplit('.', 1)
|
|
parent = resolve_path(module, path)[2]
|
|
wrapper = AttributeWrapper(attribute, factory, args, kwargs)
|
|
apply_patch(parent, attribute, wrapper)
|
|
return wrapper
|
|
|
|
# Functions for creating a simple decorator using a FunctionWrapper,
|
|
# plus short cut functions for applying wrappers to functions. These are
|
|
# for use when doing monkey patching. For a more featured way of
|
|
# creating decorators see the decorator decorator instead.
|
|
|
|
def function_wrapper(wrapper):
|
|
def _wrapper(wrapped, instance, args, kwargs):
|
|
target_wrapped = args[0]
|
|
if instance is None:
|
|
target_wrapper = wrapper
|
|
elif inspect.isclass(instance):
|
|
target_wrapper = wrapper.__get__(None, instance)
|
|
else:
|
|
target_wrapper = wrapper.__get__(instance, type(instance))
|
|
return FunctionWrapper(target_wrapped, target_wrapper)
|
|
return FunctionWrapper(wrapper, _wrapper)
|
|
|
|
def wrap_function_wrapper(module, name, wrapper):
|
|
return wrap_object(module, name, FunctionWrapper, (wrapper,))
|
|
|
|
def patch_function_wrapper(module, name):
|
|
def _wrapper(wrapper):
|
|
return wrap_object(module, name, FunctionWrapper, (wrapper,))
|
|
return _wrapper
|
|
|
|
def transient_function_wrapper(module, name):
|
|
def _decorator(wrapper):
|
|
def _wrapper(wrapped, instance, args, kwargs):
|
|
target_wrapped = args[0]
|
|
if instance is None:
|
|
target_wrapper = wrapper
|
|
elif inspect.isclass(instance):
|
|
target_wrapper = wrapper.__get__(None, instance)
|
|
else:
|
|
target_wrapper = wrapper.__get__(instance, type(instance))
|
|
def _execute(wrapped, instance, args, kwargs):
|
|
(parent, attribute, original) = resolve_path(module, name)
|
|
replacement = FunctionWrapper(original, target_wrapper)
|
|
setattr(parent, attribute, replacement)
|
|
try:
|
|
return wrapped(*args, **kwargs)
|
|
finally:
|
|
setattr(parent, attribute, original)
|
|
return FunctionWrapper(target_wrapped, _execute)
|
|
return FunctionWrapper(wrapper, _wrapper)
|
|
return _decorator
|
|
|
|
# A weak function proxy. This will work on instance methods, class
|
|
# methods, static methods and regular functions. Special treatment is
|
|
# needed for the method types because the bound method is effectively a
|
|
# transient object and applying a weak reference to one will immediately
|
|
# result in it being destroyed and the weakref callback called. The weak
|
|
# reference is therefore applied to the instance the method is bound to
|
|
# and the original function. The function is then rebound at the point
|
|
# of a call via the weak function proxy.
|
|
|
|
def _weak_function_proxy_callback(ref, proxy, callback):
|
|
if proxy._self_expired:
|
|
return
|
|
|
|
proxy._self_expired = True
|
|
|
|
# This could raise an exception. We let it propagate back and let
|
|
# the weakref.proxy() deal with it, at which point it generally
|
|
# prints out a short error message direct to stderr and keeps going.
|
|
|
|
if callback is not None:
|
|
callback(proxy)
|
|
|
|
class WeakFunctionProxy(ObjectProxy):
|
|
|
|
__slots__ = ('_self_expired', '_self_instance')
|
|
|
|
def __init__(self, wrapped, callback=None):
|
|
# We need to determine if the wrapped function is actually a
|
|
# bound method. In the case of a bound method, we need to keep a
|
|
# reference to the original unbound function and the instance.
|
|
# This is necessary because if we hold a reference to the bound
|
|
# function, it will be the only reference and given it is a
|
|
# temporary object, it will almost immediately expire and
|
|
# the weakref callback triggered. So what is done is that we
|
|
# hold a reference to the instance and unbound function and
|
|
# when called bind the function to the instance once again and
|
|
# then call it. Note that we avoid using a nested function for
|
|
# the callback here so as not to cause any odd reference cycles.
|
|
|
|
_callback = callback and functools.partial(
|
|
_weak_function_proxy_callback, proxy=self,
|
|
callback=callback)
|
|
|
|
self._self_expired = False
|
|
|
|
if isinstance(wrapped, _FunctionWrapperBase):
|
|
self._self_instance = weakref.ref(wrapped._self_instance,
|
|
_callback)
|
|
|
|
if wrapped._self_parent is not None:
|
|
super(WeakFunctionProxy, self).__init__(
|
|
weakref.proxy(wrapped._self_parent, _callback))
|
|
|
|
else:
|
|
super(WeakFunctionProxy, self).__init__(
|
|
weakref.proxy(wrapped, _callback))
|
|
|
|
return
|
|
|
|
try:
|
|
self._self_instance = weakref.ref(wrapped.__self__, _callback)
|
|
|
|
super(WeakFunctionProxy, self).__init__(
|
|
weakref.proxy(wrapped.__func__, _callback))
|
|
|
|
except AttributeError:
|
|
self._self_instance = None
|
|
|
|
super(WeakFunctionProxy, self).__init__(
|
|
weakref.proxy(wrapped, _callback))
|
|
|
|
def __call__(self, *args, **kwargs):
|
|
# We perform a boolean check here on the instance and wrapped
|
|
# function as that will trigger the reference error prior to
|
|
# calling if the reference had expired.
|
|
|
|
instance = self._self_instance and self._self_instance()
|
|
function = self.__wrapped__ and self.__wrapped__
|
|
|
|
# If the wrapped function was originally a bound function, for
|
|
# which we retained a reference to the instance and the unbound
|
|
# function we need to rebind the function and then call it. If
|
|
# not just called the wrapped function.
|
|
|
|
if instance is None:
|
|
return self.__wrapped__(*args, **kwargs)
|
|
|
|
return function.__get__(instance, type(instance))(*args, **kwargs)
|