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<div class="section" id="cell-objects">
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<span id="id1"></span><h1>Cell Objects<a class="headerlink" href="#cell-objects" title="Permalink to this headline">¶</a></h1>
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<p>“Cell” objects are used to implement variables referenced by multiple scopes.
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For each such variable, a cell object is created to store the value; the local
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variables of each stack frame that references the value contains a reference to
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the cells from outer scopes which also use that variable. When the value is
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accessed, the value contained in the cell is used instead of the cell object
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itself. This de-referencing of the cell object requires support from the
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generated byte-code; these are not automatically de-referenced when accessed.
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Cell objects are not likely to be useful elsewhere.</p>
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<dl class="type">
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<dt id="c.PyCellObject">
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<code class="descname">PyCellObject</code><a class="headerlink" href="#c.PyCellObject" title="Permalink to this definition">¶</a></dt>
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<dd><p>The C structure used for cell objects.</p>
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</dd></dl>
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<dl class="var">
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<dt id="c.PyCell_Type">
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<a class="reference internal" href="type.html#c.PyTypeObject" title="PyTypeObject">PyTypeObject</a> <code class="descname">PyCell_Type</code><a class="headerlink" href="#c.PyCell_Type" title="Permalink to this definition">¶</a></dt>
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<dd><p>The type object corresponding to cell objects.</p>
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</dd></dl>
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<dl class="function">
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<dt id="c.PyCell_Check">
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int <code class="descname">PyCell_Check</code><span class="sig-paren">(</span>ob<span class="sig-paren">)</span><a class="headerlink" href="#c.PyCell_Check" title="Permalink to this definition">¶</a></dt>
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<dd><p>Return true if <em>ob</em> is a cell object; <em>ob</em> must not be <em>NULL</em>.</p>
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</dd></dl>
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<dl class="function">
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<dt id="c.PyCell_New">
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<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="descname">PyCell_New</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *ob</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyCell_New" title="Permalink to this definition">¶</a></dt>
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<dd><em class="refcount">Return value: New reference.</em><p>Create and return a new cell object containing the value <em>ob</em>. The parameter may
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be <em>NULL</em>.</p>
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</dd></dl>
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<dl class="function">
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<dt id="c.PyCell_Get">
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<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="descname">PyCell_Get</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *cell</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyCell_Get" title="Permalink to this definition">¶</a></dt>
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<dd><em class="refcount">Return value: New reference.</em><p>Return the contents of the cell <em>cell</em>.</p>
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</dd></dl>
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<dl class="function">
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<dt id="c.PyCell_GET">
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<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="descname">PyCell_GET</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *cell</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyCell_GET" title="Permalink to this definition">¶</a></dt>
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<dd><em class="refcount">Return value: Borrowed reference.</em><p>Return the contents of the cell <em>cell</em>, but without checking that <em>cell</em> is
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non-<em>NULL</em> and a cell object.</p>
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</dd></dl>
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<dl class="function">
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<dt id="c.PyCell_Set">
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int <code class="descname">PyCell_Set</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *cell</em>, <a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *value</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyCell_Set" title="Permalink to this definition">¶</a></dt>
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<dd><p>Set the contents of the cell object <em>cell</em> to <em>value</em>. This releases the
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reference to any current content of the cell. <em>value</em> may be <em>NULL</em>. <em>cell</em>
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must be non-<em>NULL</em>; if it is not a cell object, <code class="docutils literal notranslate"><span class="pre">-1</span></code> will be returned. On
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success, <code class="docutils literal notranslate"><span class="pre">0</span></code> will be returned.</p>
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<dt id="c.PyCell_SET">
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void <code class="descname">PyCell_SET</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *cell</em>, <a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *value</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyCell_SET" title="Permalink to this definition">¶</a></dt>
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<dd><p>Sets the value of the cell object <em>cell</em> to <em>value</em>. No reference counts are
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adjusted, and no checks are made for safety; <em>cell</em> must be non-<em>NULL</em> and must
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be a cell object.</p>
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