projects / OpenSPARC-T2-SAM / blame
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| 55 | <H2><A NAME="SECTION009580000000000000000"></A><A NAME="weakref-objects"></A> | |
| 56 | <BR> | |
| 57 | 7.5.8 Weak Reference Objects | |
| 58 | </H2> | |
| 59 | ||
| 60 | <P> | |
| 61 | Python supports <em>weak references</em> as first-class objects. There | |
| 62 | are two specific object types which directly implement weak | |
| 63 | references. The first is a simple reference object, and the second | |
| 64 | acts as a proxy for the original object as much as it can. | |
| 65 | ||
| 66 | <P> | |
| 67 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td><nobr>int <b><tt id='l2h-718' xml:id='l2h-718' class="cfunction">PyWeakref_Check</tt></b>(</nobr></td><td>ob)</td></tr></table></dt> | |
| 68 | <dd> | |
| 69 | Return true if <var>ob</var> is either a reference or proxy object. | |
| 70 | ||
| 71 | <span class="versionnote">New in version 2.2.</span> | |
| 72 | ||
| 73 | </dd></dl> | |
| 74 | ||
| 75 | <P> | |
| 76 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td><nobr>int <b><tt id='l2h-719' xml:id='l2h-719' class="cfunction">PyWeakref_CheckRef</tt></b>(</nobr></td><td>ob)</td></tr></table></dt> | |
| 77 | <dd> | |
| 78 | Return true if <var>ob</var> is a reference object. | |
| 79 | ||
| 80 | <span class="versionnote">New in version 2.2.</span> | |
| 81 | ||
| 82 | </dd></dl> | |
| 83 | ||
| 84 | <P> | |
| 85 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td><nobr>int <b><tt id='l2h-720' xml:id='l2h-720' class="cfunction">PyWeakref_CheckProxy</tt></b>(</nobr></td><td>ob)</td></tr></table></dt> | |
| 86 | <dd> | |
| 87 | Return true if <var>ob</var> is a proxy object. | |
| 88 | ||
| 89 | <span class="versionnote">New in version 2.2.</span> | |
| 90 | ||
| 91 | </dd></dl> | |
| 92 | ||
| 93 | <P> | |
| 94 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td><nobr>PyObject* <b><tt id='l2h-721' xml:id='l2h-721' class="cfunction">PyWeakref_NewRef</tt></b>(</nobr></td><td>PyObject *<var>ob</var>, | |
| 95 | PyObject *<var>callback</var>)</td></tr></table></dt> | |
| 96 | <dd> | |
| 97 | <div class="refcount-info"> | |
| 98 | <span class="label">Return value:</span> | |
| 99 | <span class="value">New reference.</span> | |
| 100 | </div> | |
| 101 | Return a weak reference object for the object <var>ob</var>. This will | |
| 102 | always return a new reference, but is not guaranteed to create a new | |
| 103 | object; an existing reference object may be returned. The second | |
| 104 | parameter, <var>callback</var>, can be a callable object that receives | |
| 105 | notification when <var>ob</var> is garbage collected; it should accept a | |
| 106 | single parameter, which will be the weak reference object itself. | |
| 107 | <var>callback</var> may also be <code>None</code> or <tt class="constant">NULL</tt>. If <var>ob</var> | |
| 108 | is not a weakly-referencable object, or if <var>callback</var> is not | |
| 109 | callable, <code>None</code>, or <tt class="constant">NULL</tt>, this will return <tt class="constant">NULL</tt> and | |
| 110 | raise <tt class="exception">TypeError</tt>. | |
| 111 | ||
| 112 | <span class="versionnote">New in version 2.2.</span> | |
| 113 | ||
| 114 | </dd></dl> | |
| 115 | ||
| 116 | <P> | |
| 117 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td><nobr>PyObject* <b><tt id='l2h-722' xml:id='l2h-722' class="cfunction">PyWeakref_NewProxy</tt></b>(</nobr></td><td>PyObject *<var>ob</var>, | |
| 118 | PyObject *<var>callback</var>)</td></tr></table></dt> | |
| 119 | <dd> | |
| 120 | <div class="refcount-info"> | |
| 121 | <span class="label">Return value:</span> | |
| 122 | <span class="value">New reference.</span> | |
| 123 | </div> | |
| 124 | Return a weak reference proxy object for the object <var>ob</var>. This | |
| 125 | will always return a new reference, but is not guaranteed to create | |
| 126 | a new object; an existing proxy object may be returned. The second | |
| 127 | parameter, <var>callback</var>, can be a callable object that receives | |
| 128 | notification when <var>ob</var> is garbage collected; it should accept a | |
| 129 | single parameter, which will be the weak reference object itself. | |
| 130 | <var>callback</var> may also be <code>None</code> or <tt class="constant">NULL</tt>. If <var>ob</var> is not | |
| 131 | a weakly-referencable object, or if <var>callback</var> is not callable, | |
| 132 | <code>None</code>, or <tt class="constant">NULL</tt>, this will return <tt class="constant">NULL</tt> and raise | |
| 133 | <tt class="exception">TypeError</tt>. | |
| 134 | ||
| 135 | <span class="versionnote">New in version 2.2.</span> | |
| 136 | ||
| 137 | </dd></dl> | |
| 138 | ||
| 139 | <P> | |
| 140 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td><nobr>PyObject* <b><tt id='l2h-723' xml:id='l2h-723' class="cfunction">PyWeakref_GetObject</tt></b>(</nobr></td><td>PyObject *<var>ref</var>)</td></tr></table></dt> | |
| 141 | <dd> | |
| 142 | <div class="refcount-info"> | |
| 143 | <span class="label">Return value:</span> | |
| 144 | <span class="value">Borrowed reference.</span> | |
| 145 | </div> | |
| 146 | Return the referenced object from a weak reference, <var>ref</var>. If | |
| 147 | the referent is no longer live, returns <code>None</code>. | |
| 148 | ||
| 149 | <span class="versionnote">New in version 2.2.</span> | |
| 150 | ||
| 151 | </dd></dl> | |
| 152 | ||
| 153 | <P> | |
| 154 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td><nobr>PyObject* <b><tt id='l2h-724' xml:id='l2h-724' class="cfunction">PyWeakref_GET_OBJECT</tt></b>(</nobr></td><td>PyObject *<var>ref</var>)</td></tr></table></dt> | |
| 155 | <dd> | |
| 156 | <div class="refcount-info"> | |
| 157 | <span class="label">Return value:</span> | |
| 158 | <span class="value">Borrowed reference.</span> | |
| 159 | </div> | |
| 160 | Similar to <tt class="cfunction">PyWeakref_GetObject()</tt>, but implemented as a | |
| 161 | macro that does no error checking. | |
| 162 | ||
| 163 | <span class="versionnote">New in version 2.2.</span> | |
| 164 | ||
| 165 | </dd></dl> | |
| 166 | ||
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| 203 | <span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span> | |
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