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66 lines
2 KiB
ReStructuredText
66 lines
2 KiB
ReStructuredText
.. highlight:: c
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.. _cell-objects:
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Cell Objects
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------------
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"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.
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.. c:type:: PyCellObject
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The C structure used for cell objects.
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.. c:var:: PyTypeObject PyCell_Type
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The type object corresponding to cell objects.
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.. c:function:: int PyCell_Check(PyObject *ob)
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Return true if *ob* is a cell object; *ob* must not be ``NULL``. This
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function always succeeds.
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.. c:function:: PyObject* PyCell_New(PyObject *ob)
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Create and return a new cell object containing the value *ob*. The parameter may
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be ``NULL``.
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.. c:function:: PyObject* PyCell_Get(PyObject *cell)
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Return the contents of the cell *cell*, which can be ``NULL``.
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If *cell* is not a cell object, returns ``NULL`` with an exception set.
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.. c:function:: PyObject* PyCell_GET(PyObject *cell)
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Return the contents of the cell *cell*, but without checking that *cell* is
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non-``NULL`` and a cell object.
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.. c:function:: int PyCell_Set(PyObject *cell, PyObject *value)
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Set the contents of the cell object *cell* to *value*. This releases the
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reference to any current content of the cell. *value* may be ``NULL``. *cell*
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must be non-``NULL``.
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On success, return ``0``.
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If *cell* is not a cell object, set an exception and return ``-1``.
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.. c:function:: void PyCell_SET(PyObject *cell, PyObject *value)
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Sets the value of the cell object *cell* to *value*. No reference counts are
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adjusted, and no checks are made for safety; *cell* must be non-``NULL`` and must
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be a cell object.
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