--- rest25/library/weakref.rst	2008-12-19 16:58:07.000000000 +0900
+++ rest262/library/weakref.rst	2009-04-05 05:02:09.000000000 +0900
@@ -6,124 +6,126 @@
    :synopsis: Support for weak references and weak dictionaries.
 .. moduleauthor:: Fred L. Drake, Jr. <fdrake@acm.org>
 .. moduleauthor:: Neil Schemenauer <nas@arctrix.com>
 .. moduleauthor:: Martin von Löwis <martin@loewis.home.cs.tu-berlin.de>
 .. sectionauthor:: Fred L. Drake, Jr. <fdrake@acm.org>
 
 
 .. versionadded:: 2.1
 
 The :mod:`weakref` module allows the Python programmer to create :dfn:`weak
 references` to objects.
 
-.. % When making changes to the examples in this file, be sure to update
-.. % Lib/test/test_weakref.py::libreftest too!
+.. When making changes to the examples in this file, be sure to update
+   Lib/test/test_weakref.py::libreftest too!
 
 In the following, the term :dfn:`referent` means the object which is referred to
 by a weak reference.
 
 A weak reference to an object is not enough to keep the object alive: when the
-only remaining references to a referent are weak references, garbage collection
-is free to destroy the referent and reuse its memory for something else.  A
-primary use for weak references is to implement caches or mappings holding large
-objects, where it's desired that a large object not be kept alive solely because
-it appears in a cache or mapping.  For example, if you have a number of large
-binary image objects, you may wish to associate a name with each.  If you used a
-Python dictionary to map names to images, or images to names, the image objects
-would remain alive just because they appeared as values or keys in the
-dictionaries.  The :class:`WeakKeyDictionary` and :class:`WeakValueDictionary`
-classes supplied by the :mod:`weakref` module are an alternative, using weak
-references to construct mappings that don't keep objects alive solely because
-they appear in the mapping objects.  If, for example, an image object is a value
-in a :class:`WeakValueDictionary`, then when the last remaining references to
-that image object are the weak references held by weak mappings, garbage
-collection can reclaim the object, and its corresponding entries in weak
-mappings are simply deleted.
+only remaining references to a referent are weak references,
+:term:`garbage collection` is free to destroy the referent and reuse its memory
+for something else.  A primary use for weak references is to implement caches or
+mappings holding large objects, where it's desired that a large object not be
+kept alive solely because it appears in a cache or mapping.
+
+For example, if you have a number of large binary image objects, you may wish to
+associate a name with each.  If you used a Python dictionary to map names to
+images, or images to names, the image objects would remain alive just because
+they appeared as values or keys in the dictionaries.  The
+:class:`WeakKeyDictionary` and :class:`WeakValueDictionary` classes supplied by
+the :mod:`weakref` module are an alternative, using weak references to construct
+mappings that don't keep objects alive solely because they appear in the mapping
+objects.  If, for example, an image object is a value in a
+:class:`WeakValueDictionary`, then when the last remaining references to that
+image object are the weak references held by weak mappings, garbage collection
+can reclaim the object, and its corresponding entries in weak mappings are
+simply deleted.
 
 :class:`WeakKeyDictionary` and :class:`WeakValueDictionary` use weak references
 in their implementation, setting up callback functions on the weak references
 that notify the weak dictionaries when a key or value has been reclaimed by
 garbage collection.  Most programs should find that using one of these weak
 dictionary types is all they need -- it's not usually necessary to create your
 own weak references directly.  The low-level machinery used by the weak
 dictionary implementations is exposed by the :mod:`weakref` module for the
 benefit of advanced uses.
 
+.. note::
+
+   Weak references to an object are cleared before the object's :meth:`__del__`
+   is called, to ensure that the weak reference callback (if any) finds the
+   object still alive.
+
 Not all objects can be weakly referenced; those objects which can include class
 instances, functions written in Python (but not in C), methods (both bound and
-unbound), sets, frozensets, file objects, generators, type objects, DBcursor
-objects from the :mod:`bsddb` module, sockets, arrays, deques, and regular
-expression pattern objects.
+unbound), sets, frozensets, file objects, :term:`generator`\s, type objects,
+:class:`DBcursor` objects from the :mod:`bsddb` module, sockets, arrays, deques,
+and regular expression pattern objects.
 
 .. versionchanged:: 2.4
    Added support for files, sockets, arrays, and patterns.
 
 Several builtin types such as :class:`list` and :class:`dict` do not directly
 support weak references but can add support through subclassing::
 
    class Dict(dict):
        pass
 
-   obj = Dict(red=1, green=2, blue=3)   # this object is weak referencable
+   obj = Dict(red=1, green=2, blue=3)   # this object is weak referenceable
 
-Extension types can easily be made to support weak references; see "Weak
-Reference Support (XXX reference: ../ext/weakref-support.html)" in Extending and
-Embedding the Python Interpreter (XXX reference: ../ext/ext.html).
-
-.. % The referenced section used to appear in this document with the
-.. % \label weakref-extension.  It would be good to be able to generate a
-.. % redirect for the corresponding HTML page (weakref-extension.html)
-.. % for on-line versions of this document.
+Extension types can easily be made to support weak references; see
+:ref:`weakref-support`.
 
 
 .. class:: ref(object[, callback])
 
    Return a weak reference to *object*.  The original object can be retrieved by
    calling the reference object if the referent is still alive; if the referent is
    no longer alive, calling the reference object will cause :const:`None` to be
    returned.  If *callback* is provided and not :const:`None`, and the returned
    weakref object is still alive, the callback will be called when the object is
    about to be finalized; the weak reference object will be passed as the only
    parameter to the callback; the referent will no longer be available.
 
    It is allowable for many weak references to be constructed for the same object.
    Callbacks registered for each weak reference will be called from the most
    recently registered callback to the oldest registered callback.
 
    Exceptions raised by the callback will be noted on the standard error output,
    but cannot be propagated; they are handled in exactly the same way as exceptions
    raised from an object's :meth:`__del__` method.
 
-   Weak references are hashable if the *object* is hashable.  They will maintain
+   Weak references are :term:`hashable` if the *object* is hashable.  They will maintain
    their hash value even after the *object* was deleted.  If :func:`hash` is called
    the first time only after the *object* was deleted, the call will raise
    :exc:`TypeError`.
 
    Weak references support tests for equality, but not ordering.  If the referents
    are still alive, two references have the same equality relationship as their
    referents (regardless of the *callback*).  If either referent has been deleted,
    the references are equal only if the reference objects are the same object.
 
    .. versionchanged:: 2.4
       This is now a subclassable type rather than a factory function; it derives from
       :class:`object`.
 
 
 .. function:: proxy(object[, callback])
 
    Return a proxy to *object* which uses a weak reference.  This supports use of
    the proxy in most contexts instead of requiring the explicit dereferencing used
    with weak reference objects.  The returned object will have a type of either
    ``ProxyType`` or ``CallableProxyType``, depending on whether *object* is
-   callable.  Proxy objects are not hashable regardless of the referent; this
+   callable.  Proxy objects are not :term:`hashable` regardless of the referent; this
    avoids a number of problems related to their fundamentally mutable nature, and
    prevent their use as dictionary keys.  *callback* is the same as the parameter
    of the same name to the :func:`ref` function.
 
 
 .. function:: getweakrefcount(object)
 
    Return the number of weak references and proxies which refer to *object*.
 
 
 .. function:: getweakrefs(object)
 
@@ -131,41 +133,41 @@
 
 
 .. class:: WeakKeyDictionary([dict])
 
    Mapping class that references keys weakly.  Entries in the dictionary will be
    discarded when there is no longer a strong reference to the key.  This can be
    used to associate additional data with an object owned by other parts of an
    application without adding attributes to those objects.  This can be especially
    useful with objects that override attribute accesses.
 
    .. note::
 
-      Caution:  Because a :class:`WeakKeyDictionary` is built on top of a Python
+      Caution: Because a :class:`WeakKeyDictionary` is built on top of a Python
       dictionary, it must not change size when iterating over it.  This can be
-      difficult to ensure for a :class:`WeakKeyDictionary` because actions performed
-      by the program during iteration may cause items in the dictionary to vanish "by
-      magic" (as a side effect of garbage collection).
+      difficult to ensure for a :class:`WeakKeyDictionary` because actions
+      performed by the program during iteration may cause items in the
+      dictionary to vanish "by magic" (as a side effect of garbage collection).
 
 :class:`WeakKeyDictionary` objects have the following additional methods.  These
 expose the internal references directly.  The references are not guaranteed to
 be "live" at the time they are used, so the result of calling the references
 needs to be checked before being used.  This can be used to avoid creating
 references that will cause the garbage collector to keep the keys around longer
 than needed.
 
 
 .. method:: WeakKeyDictionary.iterkeyrefs()
 
-   Return an iterator that yields the weak references to the keys.
+   Return an :term:`iterator` that yields the weak references to the keys.
 
    .. versionadded:: 2.5
 
 
 .. method:: WeakKeyDictionary.keyrefs()
 
    Return a list of weak references to the keys.
 
    .. versionadded:: 2.5
 
 
 .. class:: WeakValueDictionary([dict])
@@ -179,25 +181,25 @@
       dictionary, it must not change size when iterating over it.  This can be
       difficult to ensure for a :class:`WeakValueDictionary` because actions performed
       by the program during iteration may cause items in the dictionary to vanish "by
       magic" (as a side effect of garbage collection).
 
 :class:`WeakValueDictionary` objects have the following additional methods.
 These method have the same issues as the :meth:`iterkeyrefs` and :meth:`keyrefs`
 methods of :class:`WeakKeyDictionary` objects.
 
 
 .. method:: WeakValueDictionary.itervaluerefs()
 
-   Return an iterator that yields the weak references to the values.
+   Return an :term:`iterator` that yields the weak references to the values.
 
    .. versionadded:: 2.5
 
 
 .. method:: WeakValueDictionary.valuerefs()
 
    Return a list of weak references to the values.
 
    .. versionadded:: 2.5
 
 
 .. data:: ReferenceType
@@ -232,38 +234,38 @@
 
    :pep:`0205` - Weak References
       The proposal and rationale for this feature, including links to earlier
       implementations and information about similar features in other languages.
 
 
 .. _weakref-objects:
 
 Weak Reference Objects
 ----------------------
 
 Weak reference objects have no attributes or methods, but do allow the referent
-to be obtained, if it still exists, by calling it::
+to be obtained, if it still exists, by calling it:
 
    >>> import weakref
    >>> class Object:
    ...     pass
    ...
    >>> o = Object()
    >>> r = weakref.ref(o)
    >>> o2 = r()
    >>> o is o2
    True
 
 If the referent no longer exists, calling the reference object returns
-:const:`None`::
+:const:`None`:
 
    >>> del o, o2
    >>> print r()
    None
 
 Testing that a weak reference object is still live should be done using the
 expression ``ref() is not None``.  Normally, application code that needs to use
 a reference object should follow this pattern::
 
    # r is a weak reference object
    o = r()
    if o is None:
@@ -309,25 +311,25 @@
 
 
 .. _weakref-example:
 
 Example
 -------
 
 This simple example shows how an application can use objects IDs to retrieve
 objects that it has seen before.  The IDs of the objects can then be used in
 other data structures without forcing the objects to remain alive, but the
 objects can still be retrieved by ID if they do.
 
-.. % Example contributed by Tim Peters.
+.. Example contributed by Tim Peters.
 
 ::
 
    import weakref
 
    _id2obj_dict = weakref.WeakValueDictionary()
 
    def remember(obj):
        oid = id(obj)
        _id2obj_dict[oid] = obj
        return oid
 
