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Patch #403985: Add support for weak-keyed dictionaries

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Martin v. Löwis 2001-02-27 18:36:56 +00:00
parent bb40dc4892
commit 5e1633365d
5 changed files with 158 additions and 21 deletions
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52
Doc/lib/libweakref.tex
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@ -3,6 +3,8 @@
\declaremodule{extension}{weakref}
\moduleauthor{Fred L. Drake, Jr.}{fdrake@acm.org}
\moduleauthor{Neil Schemenauer}{nas@arctrix.com}
\moduleauthor{Martin von L\o"wis}{martin@loewis.home.cs.tu-berlin.de}
\sectionauthor{Fred L. Drake, Jr.}{fdrake@acm.org}
\versionadded{2.1}
@ -18,13 +20,6 @@ include class instances and dictionaries. Extension types can easily
be made to support weak references; see section \ref{weakref-extension},
``Weak References in Extension Types,'' for more information.
\strong{Warning:}
The weak dictionaries provided in the current implementation and
described below are subject to change. They are included to solicit
feedback and usage experience, and may be changed or removed in the
final version.
\strong{Warning:}
The desired semantics of weak-reference proxy objects are not
completely clear; it is very difficult to create proxies which behave
@ -32,9 +27,6 @@ exactly like the type of the referent. The details of these objects
are likely to change to some degree before the final release as
experience reports become available.
Please send specific feedback on this module to Fred Drake at
\email{fdrake@acm.org}.
\begin{funcdesc}{ref}{object\optional{, callback}}
Return a weak reference to \var{object}. If \var{callback} is
@ -53,15 +45,36 @@ Please send specific feedback on this module to Fred Drake at
error output, but cannot be propagated; they are handled in exactly
the same way as exceptions raised from an object's
\method{__del__()} method.
Weak references are hashable if the \var{object} is hashable. They
will maintain their hash value even after the \var{object} was
deleted. If \function{hash()} is called the first time only after
the \var{object} was deleted, the call will raise
\exception{TypeError}.
Weak references support test for equality, but not ordering. If the
\var{object} is still alive, to references are equal if the objects
are equal (regardless of the \var{callback}). If the \var{object}
has been deleted, they are equal iff they are identical.
\end{funcdesc}
\begin{funcdesc}{mapping}{\optional{dict}}
\begin{funcdesc}{mapping}{\optional{dict\optional{, weakkeys=0}}}
Return a weak dictionary. If \var{dict} is given and not
\code{None}, the new dictionary will contain the items contained in
\var{dict}. The values from \var{dict} must be weakly referencable;
if any values which would be inserted into the new mapping are not
weakly referencable, \exception{TypeError} will be raised and the
new mapping will be empty.
If the \var{weakkeys} argument is not given or zero, the values in
the dictionary are weak. That means the entries in the dictionary
will be discarded when no strong reference to the value exists
anymore.
If the \var{weakkeys} argument is nonzero, the keys in the
dictionary are weak, i.e. the entry in the dictionary is discarded
when the last strong reference to the key is discarded.
\end{funcdesc}
\begin{funcdesc}{proxy}{object\optional{, callback}}
@ -87,9 +100,16 @@ Please send specific feedback on this module to Fred Drake at
\var{object}.
\end{funcdesc}
\begin{classdesc}{WeakDictionary}{\optional{dict}}
The class of the mapping objects returned by \function{mapping()}.
This can be used for subclassing the implementation if needed.
\begin{classdesc}{WeakKeyDictionary}{\optional{dict}}
The class of the mapping objects returned by \function{mapping()}
when \var{weakkeys} is true. This can be used for subclassing the
implementation if needed.
\end{classdesc}
\begin{classdesc}{WeakValueDictionary}{\optional{dict}}
The class of the mapping objects returned by \function{mapping()}
when \var{weakkeys} if false. This can be used for subclassing the
implementation if needed.
\end{classdesc}
\begin{datadesc}{ReferenceType}
@ -187,8 +207,8 @@ For example, the instance type is defined with the following structure:
typedef struct {
PyObject_HEAD
PyClassObject *in_class; /* The class object */
PyObject *in_dict; /* A dictionary */
PyObject *in_weakreflist; /* List of weak references */
PyObject *in_dict; /* A dictionary */
PyObject *in_weakreflist; /* List of weak references */
} PyInstanceObject;
\end{verbatim}