Make weak references subclassable:

- weakref.ref and weakref.ReferenceType will become aliases for each
  other

- weakref.ref will be a modern, new-style class with proper __new__
  and __init__ methods

- weakref.WeakValueDictionary will have a lighter memory footprint,
  using a new weakref.ref subclass to associate the key with the
  value, allowing us to have only a single object of overhead for each
  dictionary entry (currently, there are 3 objects of overhead per
  entry: a weakref to the value, a weakref to the dictionary, and a
  function object used as a weakref callback; the weakref to the
  dictionary could be avoided without this change)

- a new macro, PyWeakref_CheckRefExact(), will be added

- PyWeakref_CheckRef() will check for subclasses of weakref.ref

This closes SF patch #983019.

1 files changed, 3 insertions, 0 deletions

diff --git a/Objects/object.c b/Objects/object.c
index 1c0efdd..26149a7 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -1802,6 +1802,9 @@ _Py_ReadyTypes(void)
 	if (PyType_Ready(&PyType_Type) < 0)
 		Py_FatalError("Can't initialize 'type'");
 
+	if (PyType_Ready(&_PyWeakref_RefType) < 0)
+		Py_FatalError("Can't initialize 'weakref'");
+
 	if (PyType_Ready(&PyBool_Type) < 0)
 		Py_FatalError("Can't initialize 'bool'");