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annotate Doc/c-api/weakref.rst @ 54294:dba767bc3155 legacy-trunk

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remove mention of old ctypes version
author Benjamin Peterson <benjamin@python.org>
date Sat, 23 May 2009 20:59:09 +0000
parents 13dc65fe8599
children 595676e466c0
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1 .. highlightlang:: c
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3 .. _weakrefobjects:
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4
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5 Weak Reference Objects
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6 ----------------------
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7
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8 Python supports *weak references* as first-class objects. There are two
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9 specific object types which directly implement weak references. The first is a
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10 simple reference object, and the second acts as a proxy for the original object
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11 as much as it can.
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14 .. cfunction:: int PyWeakref_Check(ob)
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16 Return true if *ob* is either a reference or proxy object.
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18 .. versionadded:: 2.2
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21 .. cfunction:: int PyWeakref_CheckRef(ob)
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23 Return true if *ob* is a reference object.
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25 .. versionadded:: 2.2
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28 .. cfunction:: int PyWeakref_CheckProxy(ob)
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30 Return true if *ob* is a proxy object.
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32 .. versionadded:: 2.2
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35 .. cfunction:: PyObject* PyWeakref_NewRef(PyObject *ob, PyObject *callback)
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37 Return a weak reference object for the object *ob*. This will always return
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38 a new reference, but is not guaranteed to create a new object; an existing
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39 reference object may be returned. The second parameter, *callback*, can be a
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40 callable object that receives notification when *ob* is garbage collected; it
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41 should accept a single parameter, which will be the weak reference object
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42 itself. *callback* may also be ``None`` or *NULL*. If *ob* is not a
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43 weakly-referencable object, or if *callback* is not callable, ``None``, or
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44 *NULL*, this will return *NULL* and raise :exc:`TypeError`.
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46 .. versionadded:: 2.2
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49 .. cfunction:: PyObject* PyWeakref_NewProxy(PyObject *ob, PyObject *callback)
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51 Return a weak reference proxy object for the object *ob*. This will always
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52 return a new reference, but is not guaranteed to create a new object; an
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53 existing proxy object may be returned. The second parameter, *callback*, can
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54 be a callable object that receives notification when *ob* is garbage
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55 collected; it should accept a single parameter, which will be the weak
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56 reference object itself. *callback* may also be ``None`` or *NULL*. If *ob*
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57 is not a weakly-referencable object, or if *callback* is not callable,
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58 ``None``, or *NULL*, this will return *NULL* and raise :exc:`TypeError`.
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60 .. versionadded:: 2.2
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63 .. cfunction:: PyObject* PyWeakref_GetObject(PyObject *ref)
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64
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65 Return the referenced object from a weak reference, *ref*. If the referent is
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66 no longer live, returns ``None``.
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68 .. versionadded:: 2.2
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71 .. cfunction:: PyObject* PyWeakref_GET_OBJECT(PyObject *ref)
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73 Similar to :cfunc:`PyWeakref_GetObject`, but implemented as a macro that does no
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74 error checking.
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76 .. versionadded:: 2.2