PEP 205, Weak References -- initial checkin.
diff --git a/Lib/weakref.py b/Lib/weakref.py
new file mode 100644
index 0000000..f6e07c9
--- /dev/null
+++ b/Lib/weakref.py
@@ -0,0 +1,117 @@
+"""Weak reference support for Python.
+
+This module is an implementation of PEP 205:
+
+http://python.sourceforge.net/peps/pep-0205.html
+"""
+
+import UserDict
+
+from _weakref import \
+ getweakrefcount, \
+ getweakrefs, \
+ ref, \
+ proxy, \
+ ReferenceError, \
+ CallableProxyType, \
+ ProxyType, \
+ ReferenceType
+
+ProxyTypes = (ProxyType, CallableProxyType)
+
+
+def mapping(dict=None):
+ return WeakDictionary(dict)
+
+
+class WeakDictionary(UserDict.UserDict):
+
+ # We inherit the constructor without worrying about the input
+ # dictionary; since it uses our .update() method, we get the right
+ # checks (if the other dictionary is a WeakDictionary, objects are
+ # unwrapped on the way out, and we always wrap on the way in).
+
+ def __getitem__(self, key):
+ o = self.data.get(key)()
+ if o is None:
+ raise KeyError, key
+ else:
+ return o
+
+ def __repr__(self):
+ return "<WeakDictionary at %s>" % id(self)
+
+ def __setitem__(self, key, value):
+ def remove(o, data=self.data, key=key):
+ del data[key]
+ self.data[key] = ref(value, remove)
+
+ def copy(self):
+ new = WeakDictionary()
+ for key, ref in self.data.items():
+ o = ref()
+ if o is not None:
+ new[key] = o
+
+ def get(self, key, default):
+ try:
+ ref = self.data[key]
+ except KeyError:
+ return default
+ else:
+ o = ref()
+ if o is None:
+ # This should only happen
+ return default
+ else:
+ return o
+
+ def items(self):
+ L = self.data.items()
+ for i in range(len(L)):
+ key, ref = L[i]
+ o = ref()
+ if o is not None:
+ L[i] = key, o
+ return L
+
+ def popitem(self):
+ while 1:
+ key, ref = self.data.popitem()
+ o = ref()
+ if o is not None:
+ return key, o
+
+ def setdefault(self, key, default):
+ try:
+ ref = self.data[key]
+ except KeyError:
+ def remove(o, data=self.data, key=key):
+ del data[key]
+ ref = ref(default, remove)
+ self.data[key] = ref
+ return default
+ else:
+ return ref()
+
+ def update(self, dict):
+ d = self.data
+ L = []
+ for key, o in dict.items():
+ def remove(o, data=d, key=key):
+ del data[key]
+ L.append(key, ref(o, remove))
+ for key, r in L:
+ d[key] = r
+
+ def values(self):
+ L = []
+ for ref in self.data.values():
+ o = ref()
+ if o is not None:
+ L.append(o)
+ return L
+
+
+# no longer needed
+del UserDict