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authorGeorg Brandl <georg@python.org>2008-01-20 09:30:57 +0000
committerGeorg Brandl <georg@python.org>2008-01-20 09:30:57 +0000
commit4fb49ac6cce85c53588cfc8e2a776ae6ed70b047 (patch)
tree1d90f697819808a9fee7df5de77d45639f28439c /Doc/c-api/allocation.rst
parent70c52b12b8ed832d3a0fa7fa4d76cd3435ce5fe4 (diff)
downloadcpython-4fb49ac6cce85c53588cfc8e2a776ae6ed70b047.tar.gz
Split C API docs in Py3k branch.
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+.. highlightlang:: c
+
+.. _allocating-objects:
+
+Allocating Objects on the Heap
+==============================
+
+
+.. cfunction:: PyObject* _PyObject_New(PyTypeObject *type)
+
+
+.. cfunction:: PyVarObject* _PyObject_NewVar(PyTypeObject *type, Py_ssize_t size)
+
+
+.. cfunction:: PyObject* PyObject_Init(PyObject *op, PyTypeObject *type)
+
+ Initialize a newly-allocated object *op* with its type and initial reference.
+ Returns the initialized object. If *type* indicates that the object
+ participates in the cyclic garbage detector, it is added to the detector's set
+ of observed objects. Other fields of the object are not affected.
+
+
+.. cfunction:: PyVarObject* PyObject_InitVar(PyVarObject *op, PyTypeObject *type, Py_ssize_t size)
+
+ This does everything :cfunc:`PyObject_Init` does, and also initializes the
+ length information for a variable-size object.
+
+
+.. cfunction:: TYPE* PyObject_New(TYPE, PyTypeObject *type)
+
+ Allocate a new Python object using the C structure type *TYPE* and the Python
+ type object *type*. Fields not defined by the Python object header are not
+ initialized; the object's reference count will be one. The size of the memory
+ allocation is determined from the :attr:`tp_basicsize` field of the type object.
+
+
+.. cfunction:: TYPE* PyObject_NewVar(TYPE, PyTypeObject *type, Py_ssize_t size)
+
+ Allocate a new Python object using the C structure type *TYPE* and the Python
+ type object *type*. Fields not defined by the Python object header are not
+ initialized. The allocated memory allows for the *TYPE* structure plus *size*
+ fields of the size given by the :attr:`tp_itemsize` field of *type*. This is
+ useful for implementing objects like tuples, which are able to determine their
+ size at construction time. Embedding the array of fields into the same
+ allocation decreases the number of allocations, improving the memory management
+ efficiency.
+
+
+.. cfunction:: void PyObject_Del(PyObject *op)
+
+ Releases memory allocated to an object using :cfunc:`PyObject_New` or
+ :cfunc:`PyObject_NewVar`. This is normally called from the :attr:`tp_dealloc`
+ handler specified in the object's type. The fields of the object should not be
+ accessed after this call as the memory is no longer a valid Python object.
+
+
+.. cfunction:: PyObject* Py_InitModule(char *name, PyMethodDef *methods)
+
+ Create a new module object based on a name and table of functions, returning
+ the new module object; the *methods* argument can be *NULL* if no methods are
+ to be defined for the module.
+
+
+.. cfunction:: PyObject* Py_InitModule3(char *name, PyMethodDef *methods, char *doc)
+
+ Create a new module object based on a name and table of functions, returning
+ the new module object. The *methods* argument can be *NULL* if no methods
+ are to be defined for the module. If *doc* is non-*NULL*, it will be used to
+ define the docstring for the module.
+
+
+.. cfunction:: PyObject* Py_InitModule4(char *name, PyMethodDef *methods, char *doc, PyObject *self, int apiver)
+
+ Create a new module object based on a name and table of functions, returning
+ the new module object. The *methods* argument can be *NULL* if no methods
+ are to be defined for the module. If *doc* is non-*NULL*, it will be used to
+ define the docstring for the module. If *self* is non-*NULL*, it will passed
+ to the functions of the module as their (otherwise *NULL*) first parameter.
+ (This was added as an experimental feature, and there are no known uses in
+ the current version of Python.) For *apiver*, the only value which should be
+ passed is defined by the constant :const:`PYTHON_API_VERSION`.
+
+ .. note::
+
+ Most uses of this function should probably be using the :cfunc:`Py_InitModule3`
+ instead; only use this if you are sure you need it.
+
+
+.. cvar:: PyObject _Py_NoneStruct
+
+ Object which is visible in Python as ``None``. This should only be accessed
+ using the :cmacro:`Py_None` macro, which evaluates to a pointer to this
+ object.