Update 2025-04-24_11:44:19

venv/lib/python3.11/site-packages/wrapt/weakrefs.py

@@ -0,0 +1,98 @@
+import functools
+import weakref
+
+from .__wrapt__ import ObjectProxy, _FunctionWrapperBase
+
+# 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__(*args, **kwargs):
+        def _unpack_self(self, *args):
+            return self, args
+
+        self, args = _unpack_self(*args)
+
+        # 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)