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