Merged revisions 75580 via svnmerge from

svn+ssh://pythondev@svn.python.org/python/trunk

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  r75580 | georg.brandl | 2009-10-21 09:15:59 +0200 (Mi, 21 Okt 2009) | 1 line

  #7170: fix explanation about non-weakrefable builtin types.
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Doc/library/weakref.rst

@@ -72,6 +72,10 @@ support weak references but can add support through subclassing::
 
    obj = Dict(red=1, green=2, blue=3)   # this object is weak referenceable
 
+Other built-in types such as :class:`tuple` and :class:`int` do not support
+weak references even when subclassed (those types implemented as a
+:ctype:`PyVarObject`).
+
 Extension types can easily be made to support weak references; see
 :ref:`weakref-support`.