import sys import operator import inspect PY2 = sys.version_info[0] == 2 if PY2: string_types = basestring, else: string_types = str, def with_metaclass(meta, *bases): """Create a base class with a metaclass.""" return meta("NewBase", bases, {}) class _ObjectProxyMethods(object): # We use properties to override the values of __module__ and # __doc__. If we add these in ObjectProxy, the derived class # __dict__ will still be setup to have string variants of these # attributes and the rules of descriptors means that they appear to # take precedence over the properties in the base class. To avoid # that, we copy the properties into the derived class type itself # via a meta class. In that way the properties will always take # precedence. @property def __module__(self): return self.__wrapped__.__module__ @__module__.setter def __module__(self, value): self.__wrapped__.__module__ = value @property def __doc__(self): return self.__wrapped__.__doc__ @__doc__.setter def __doc__(self, value): self.__wrapped__.__doc__ = value # We similar use a property for __dict__. We need __dict__ to be # explicit to ensure that vars() works as expected. @property def __dict__(self): return self.__wrapped__.__dict__ # Need to also propagate the special __weakref__ attribute for case # where decorating classes which will define this. If do not define # it and use a function like inspect.getmembers() on a decorator # class it will fail. This can't be in the derived classes. @property def __weakref__(self): return self.__wrapped__.__weakref__ class _ObjectProxyMetaType(type): def __new__(cls, name, bases, dictionary): # Copy our special properties into the class so that they # always take precedence over attributes of the same name added # during construction of a derived class. This is to save # duplicating the implementation for them in all derived classes. dictionary.update(vars(_ObjectProxyMethods)) return type.__new__(cls, name, bases, dictionary) class ObjectProxy(with_metaclass(_ObjectProxyMetaType)): __slots__ = '__wrapped__' def __init__(self, wrapped): object.__setattr__(self, '__wrapped__', wrapped) # Python 3.2+ has the __qualname__ attribute, but it does not # allow it to be overridden using a property and it must instead # be an actual string object instead. try: object.__setattr__(self, '__qualname__', wrapped.__qualname__) except AttributeError: pass # Python 3.10 onwards also does not allow itself to be overridden # using a property and it must instead be set explicitly. try: object.__setattr__(self, '__annotations__', wrapped.__annotations__) except AttributeError: pass def __self_setattr__(self, name, value): object.__setattr__(self, name, value) @property def __name__(self): return self.__wrapped__.__name__ @__name__.setter def __name__(self, value): self.__wrapped__.__name__ = value @property def __class__(self): return self.__wrapped__.__class__ @__class__.setter def __class__(self, value): self.__wrapped__.__class__ = value def __dir__(self): return dir(self.__wrapped__) def __str__(self): return str(self.__wrapped__) if not PY2: def __bytes__(self): return bytes(self.__wrapped__) def __repr__(self): return '<{} at 0x{:x} for {} at 0x{:x}>'.format( type(self).__name__, id(self), type(self.__wrapped__).__name__, id(self.__wrapped__)) def __reversed__(self): return reversed(self.__wrapped__) if not PY2: def __round__(self): return round(self.__wrapped__) if sys.hexversion >= 0x03070000: def __mro_entries__(self, bases): return (self.__wrapped__,) def __lt__(self, other): return self.__wrapped__ < other def __le__(self, other): return self.__wrapped__ <= other def __eq__(self, other): return self.__wrapped__ == other def __ne__(self, other): return self.__wrapped__ != other def __gt__(self, other): return self.__wrapped__ > other def __ge__(self, other): return self.__wrapped__ >= other def __hash__(self): return hash(self.__wrapped__) def __nonzero__(self): return bool(self.__wrapped__) def __bool__(self): return bool(self.__wrapped__) def __setattr__(self, name, value): if name.startswith('_self_'): object.__setattr__(self, name, value) elif name == '__wrapped__': object.__setattr__(self, name, value) try: object.__delattr__(self, '__qualname__') except AttributeError: pass try: object.__setattr__(self, '__qualname__', value.__qualname__) except AttributeError: pass try: object.__delattr__(self, '__annotations__') except AttributeError: pass try: object.__setattr__(self, '__annotations__', value.__annotations__) except AttributeError: pass elif name == '__qualname__': setattr(self.__wrapped__, name, value) object.__setattr__(self, name, value) elif name == '__annotations__': setattr(self.__wrapped__, name, value) object.__setattr__(self, name, value) elif hasattr(type(self), name): object.__setattr__(self, name, value) else: setattr(self.__wrapped__, name, value) def __getattr__(self, name): # If we are being to lookup '__wrapped__' then the # '__init__()' method cannot have been called. if name == '__wrapped__': raise ValueError('wrapper has not been initialised') return getattr(self.__wrapped__, name) def __delattr__(self, name): if name.startswith('_self_'): object.__delattr__(self, name) elif name == '__wrapped__': raise TypeError('__wrapped__ must be an object') elif name == '__qualname__': object.__delattr__(self, name) delattr(self.__wrapped__, name) elif hasattr(type(self), name): object.__delattr__(self, name) else: delattr(self.__wrapped__, name) def __add__(self, other): return self.__wrapped__ + other def __sub__(self, other): return self.__wrapped__ - other def __mul__(self, other): return self.__wrapped__ * other def __div__(self, other): return operator.div(self.__wrapped__, other) def __truediv__(self, other): return operator.truediv(self.__wrapped__, other) def __floordiv__(self, other): return self.__wrapped__ // other def __mod__(self, other): return self.__wrapped__ % other def __divmod__(self, other): return divmod(self.__wrapped__, other) def __pow__(self, other, *args): return pow(self.__wrapped__, other, *args) def __lshift__(self, other): return self.__wrapped__ << other def __rshift__(self, other): return self.__wrapped__ >> other def __and__(self, other): return self.__wrapped__ & other def __xor__(self, other): return self.__wrapped__ ^ other def __or__(self, other): return self.__wrapped__ | other def __radd__(self, other): return other + self.__wrapped__ def __rsub__(self, other): return other - self.__wrapped__ def __rmul__(self, other): return other * self.__wrapped__ def __rdiv__(self, other): return operator.div(other, self.__wrapped__) def __rtruediv__(self, other): return operator.truediv(other, self.__wrapped__) def __rfloordiv__(self, other): return other // self.__wrapped__ def __rmod__(self, other): return other % self.__wrapped__ def __rdivmod__(self, other): return divmod(other, self.__wrapped__) def __rpow__(self, other, *args): return pow(other, self.__wrapped__, *args) def __rlshift__(self, other): return other << self.__wrapped__ def __rrshift__(self, other): return other >> self.__wrapped__ def __rand__(self, other): return other & self.__wrapped__ def __rxor__(self, other): return other ^ self.__wrapped__ def __ror__(self, other): return other | self.__wrapped__ def __iadd__(self, other): self.__wrapped__ += other return self def __isub__(self, other): self.__wrapped__ -= other return self def __imul__(self, other): self.__wrapped__ *= other return self def __idiv__(self, other): self.__wrapped__ = operator.idiv(self.__wrapped__, other) return self def __itruediv__(self, other): self.__wrapped__ = operator.itruediv(self.__wrapped__, other) return self def __ifloordiv__(self, other): self.__wrapped__ //= other return self def __imod__(self, other): self.__wrapped__ %= other return self def __ipow__(self, other): self.__wrapped__ **= other return self def __ilshift__(self, other): self.__wrapped__ <<= other return self def __irshift__(self, other): self.__wrapped__ >>= other return self def __iand__(self, other): self.__wrapped__ &= other return self def __ixor__(self, other): self.__wrapped__ ^= other return self def __ior__(self, other): self.__wrapped__ |= other return self def __neg__(self): return -self.__wrapped__ def __pos__(self): return +self.__wrapped__ def __abs__(self): return abs(self.__wrapped__) def __invert__(self): return ~self.__wrapped__ def __int__(self): return int(self.__wrapped__) def __long__(self): return long(self.__wrapped__) def __float__(self): return float(self.__wrapped__) def __complex__(self): return complex(self.__wrapped__) def __oct__(self): return oct(self.__wrapped__) def __hex__(self): return hex(self.__wrapped__) def __index__(self): return operator.index(self.__wrapped__) def __len__(self): return len(self.__wrapped__) def __contains__(self, value): return value in self.__wrapped__ def __getitem__(self, key): return self.__wrapped__[key] def __setitem__(self, key, value): self.__wrapped__[key] = value def __delitem__(self, key): del self.__wrapped__[key] def __getslice__(self, i, j): return self.__wrapped__[i:j] def __setslice__(self, i, j, value): self.__wrapped__[i:j] = value def __delslice__(self, i, j): del self.__wrapped__[i:j] def __enter__(self): return self.__wrapped__.__enter__() def __exit__(self, *args, **kwargs): return self.__wrapped__.__exit__(*args, **kwargs) def __iter__(self): return iter(self.__wrapped__) def __copy__(self): raise NotImplementedError('object proxy must define __copy__()') def __deepcopy__(self, memo): raise NotImplementedError('object proxy must define __deepcopy__()') def __reduce__(self): raise NotImplementedError( 'object proxy must define __reduce_ex__()') def __reduce_ex__(self, protocol): raise NotImplementedError( 'object proxy must define __reduce_ex__()') class CallableObjectProxy(ObjectProxy): def __call__(*args, **kwargs): def _unpack_self(self, *args): return self, args self, args = _unpack_self(*args) return self.__wrapped__(*args, **kwargs) class PartialCallableObjectProxy(ObjectProxy): def __init__(*args, **kwargs): def _unpack_self(self, *args): return self, args self, args = _unpack_self(*args) if len(args) < 1: raise TypeError('partial type takes at least one argument') wrapped, args = args[0], args[1:] if not callable(wrapped): raise TypeError('the first argument must be callable') super(PartialCallableObjectProxy, self).__init__(wrapped) self._self_args = args self._self_kwargs = kwargs def __call__(*args, **kwargs): def _unpack_self(self, *args): return self, args self, args = _unpack_self(*args) _args = self._self_args + args _kwargs = dict(self._self_kwargs) _kwargs.update(kwargs) return self.__wrapped__(*_args, **_kwargs) class _FunctionWrapperBase(ObjectProxy): __slots__ = ('_self_instance', '_self_wrapper', '_self_enabled', '_self_binding', '_self_parent') def __init__(self, wrapped, instance, wrapper, enabled=None, binding='function', parent=None): super(_FunctionWrapperBase, self).__init__(wrapped) object.__setattr__(self, '_self_instance', instance) object.__setattr__(self, '_self_wrapper', wrapper) object.__setattr__(self, '_self_enabled', enabled) object.__setattr__(self, '_self_binding', binding) object.__setattr__(self, '_self_parent', parent) def __get__(self, instance, owner): # This method is actually doing double duty for both unbound and # bound derived wrapper classes. It should possibly be broken up # and the distinct functionality moved into the derived classes. # Can't do that straight away due to some legacy code which is # relying on it being here in this base class. # # The distinguishing attribute which determines whether we are # being called in an unbound or bound wrapper is the parent # attribute. If binding has never occurred, then the parent will # be None. # # First therefore, is if we are called in an unbound wrapper. In # this case we perform the binding. # # We have one special case to worry about here. This is where we # are decorating a nested class. In this case the wrapped class # would not have a __get__() method to call. In that case we # simply return self. # # Note that we otherwise still do binding even if instance is # None and accessing an unbound instance method from a class. # This is because we need to be able to later detect that # specific case as we will need to extract the instance from the # first argument of those passed in. if self._self_parent is None: if not inspect.isclass(self.__wrapped__): descriptor = self.__wrapped__.__get__(instance, owner) return self.__bound_function_wrapper__(descriptor, instance, self._self_wrapper, self._self_enabled, self._self_binding, self) return self # Now we have the case of binding occurring a second time on what # was already a bound function. In this case we would usually # return ourselves again. This mirrors what Python does. # # The special case this time is where we were originally bound # with an instance of None and we were likely an instance # method. In that case we rebind against the original wrapped # function from the parent again. if self._self_instance is None and self._self_binding == 'function': descriptor = self._self_parent.__wrapped__.__get__( instance, owner) return self._self_parent.__bound_function_wrapper__( descriptor, instance, self._self_wrapper, self._self_enabled, self._self_binding, self._self_parent) return self def __call__(*args, **kwargs): def _unpack_self(self, *args): return self, args self, args = _unpack_self(*args) # If enabled has been specified, then evaluate it at this point # and if the wrapper is not to be executed, then simply return # the bound function rather than a bound wrapper for the bound # function. When evaluating enabled, if it is callable we call # it, otherwise we evaluate it as a boolean. if self._self_enabled is not None: if callable(self._self_enabled): if not self._self_enabled(): return self.__wrapped__(*args, **kwargs) elif not self._self_enabled: return self.__wrapped__(*args, **kwargs) # This can occur where initial function wrapper was applied to # a function that was already bound to an instance. In that case # we want to extract the instance from the function and use it. if self._self_binding in ('function', 'classmethod'): if self._self_instance is None: instance = getattr(self.__wrapped__, '__self__', None) if instance is not None: return self._self_wrapper(self.__wrapped__, instance, args, kwargs) # This is generally invoked when the wrapped function is being # called as a normal function and is not bound to a class as an # instance method. This is also invoked in the case where the # wrapped function was a method, but this wrapper was in turn # wrapped using the staticmethod decorator. return self._self_wrapper(self.__wrapped__, self._self_instance, args, kwargs) def __set_name__(self, owner, name): # This is a special method use to supply information to # descriptors about what the name of variable in a class # definition is. Not wanting to add this to ObjectProxy as not # sure of broader implications of doing that. Thus restrict to # FunctionWrapper used by decorators. if hasattr(self.__wrapped__, "__set_name__"): self.__wrapped__.__set_name__(owner, name) def __instancecheck__(self, instance): # This is a special method used by isinstance() to make checks # instance of the `__wrapped__`. return isinstance(instance, self.__wrapped__) def __subclasscheck__(self, subclass): # This is a special method used by issubclass() to make checks # about inheritance of classes. We need to upwrap any object # proxy. Not wanting to add this to ObjectProxy as not sure of # broader implications of doing that. Thus restrict to # FunctionWrapper used by decorators. if hasattr(subclass, "__wrapped__"): return issubclass(subclass.__wrapped__, self.__wrapped__) else: return issubclass(subclass, self.__wrapped__) class BoundFunctionWrapper(_FunctionWrapperBase): def __call__(*args, **kwargs): def _unpack_self(self, *args): return self, args self, args = _unpack_self(*args) # If enabled has been specified, then evaluate it at this point # and if the wrapper is not to be executed, then simply return # the bound function rather than a bound wrapper for the bound # function. When evaluating enabled, if it is callable we call # it, otherwise we evaluate it as a boolean. if self._self_enabled is not None: if callable(self._self_enabled): if not self._self_enabled(): return self.__wrapped__(*args, **kwargs) elif not self._self_enabled: return self.__wrapped__(*args, **kwargs) # We need to do things different depending on whether we are # likely wrapping an instance method vs a static method or class # method. if self._self_binding == 'function': if self._self_instance is None: # This situation can occur where someone is calling the # instancemethod via the class type and passing the instance # as the first argument. We need to shift the args before # making the call to the wrapper and effectively bind the # instance to the wrapped function using a partial so the # wrapper doesn't see anything as being different. if not args: raise TypeError('missing 1 required positional argument') instance, args = args[0], args[1:] wrapped = PartialCallableObjectProxy(self.__wrapped__, instance) return self._self_wrapper(wrapped, instance, args, kwargs) return self._self_wrapper(self.__wrapped__, self._self_instance, args, kwargs) else: # As in this case we would be dealing with a classmethod or # staticmethod, then _self_instance will only tell us whether # when calling the classmethod or staticmethod they did it via an # instance of the class it is bound to and not the case where # done by the class type itself. We thus ignore _self_instance # 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)