Support for extension codes. (By accident I checked in the tests first.)
diff --git a/Lib/copy_reg.py b/Lib/copy_reg.py
index 8a3550a..1276564 100644
--- a/Lib/copy_reg.py
+++ b/Lib/copy_reg.py
@@ -70,3 +70,62 @@
return _reconstructor, args, dict
else:
return _reconstructor, args
+
+# A registry of extension codes. This is an ad-hoc compression
+# mechanism. Whenever a global reference to <module>, <name> is about
+# to be pickled, the (<module>, <name>) tuple is looked up here to see
+# if it is a registered extension code for it. Extension codes are
+# universal, so that the meaning of a pickle does not depend on
+# context. (There are also some codes reserved for local use that
+# don't have this restriction.) Codes are positive ints; 0 is
+# reserved.
+
+extension_registry = {} # key -> code
+inverted_registry = {} # code -> key
+extension_cache = {} # code -> object
+
+def add_extension(module, name, code):
+ """Register an extension code."""
+ code = int(code)
+ if not 1 <= code < 0x7fffffff:
+ raise ValueError, "code out of range"
+ key = (module, name)
+ if (extension_registry.get(key) == code and
+ inverted_registry.get(code) == key):
+ return # Redundant registrations are benign
+ if key in extension_registry:
+ raise ValueError("key %s is already registered with code %s" %
+ (key, extension_registry[key]))
+ if code in inverted_registry:
+ raise ValueError("code %s is already in use for key %s" %
+ (code, inverted_registry[code]))
+ extension_registry[key] = code
+ inverted_registry[code] = key
+
+def remove_extension(module, name, code):
+ """Unregister an extension code. For testing only."""
+ key = (module, name)
+ if (extension_registry.get(key) != code or
+ inverted_registry.get(code) != key):
+ raise ValueError("key %s is not registered with code %s" %
+ (key, code))
+ del extension_registry[key]
+ del inverted_registry[code]
+ if code in extension_cache:
+ del extension_cache[code]
+
+def clear_extension_cache():
+ extension_cache.clear()
+
+# Standard extension code assignments
+
+# Reserved ranges
+
+# First Last Count Purpose
+# 1 127 127 Reserved for Python standard library
+# 128 191 64 Reserved for Zope 3
+# 192 239 48 Reserved for 3rd parties
+# 240 255 16 Reserved for private use (will never be assigned)
+# 256 Inf Inf Reserved for future assignment
+
+# Extension codes are assigned by the Python Software Foundation.