7.5.10 Cell Objects

``Cell'' objects are used to implement variables referenced by multiple scopes. For each such variable, a cell object is created to store the value; the local variables of each stack frame that references the value contains a reference to the cells from outer scopes which also use that variable. When the value is accessed, the value contained in the cell is used instead of the cell object itself. This de-referencing of the cell object requires support from the generated byte-code; these are not automatically de-referenced when accessed. Cell objects are not likely to be useful elsewhere.

PyCellObject: The C structure used for cell objects.

PyTypeObject PyCell_Type: The type object corresponding to cell objects

int PyCell_Check(ob): Return true if ob is a cell object; ob must not be NULL.

PyObject* PyCell_New(PyObject *ob): Return value: New reference.
Create and return a new cell object containing the value ob. The parameter may be NULL.

PyObject* PyCell_Get(PyObject *cell): Return value: New reference.
Return the contents of the cell cell.

PyObject* PyCell_GET(PyObject *cell): Return value: Borrowed reference.
Return the contents of the cell cell, but without checking that cell is non-NULL and a call object.

int PyCell_Set(PyObject *cell, PyObject *value): Set the contents of the cell object cell to value. This releases the reference to any current content of the cell. value may be NULL. cell must be non-NULL; if it is not a cell object, -1 will be returned. On success, 0 will be returned.

void PyCell_SET(PyObject *cell, PyObject *value): Sets the value of the cell object cell to value. No reference counts are adjusted, and no checks are made for safety; cell must be non-NULL and must be a cell object.

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