Allocating Objects on the Heap

.. c:function:: PyObject* _PyObject_New(PyTypeObject *type)

.. c:function:: PyVarObject* _PyObject_NewVar(PyTypeObject *type, Py_ssize_t size)

.. c:function:: PyObject* PyObject_Init(PyObject *op, PyTypeObject *type)

Initialize a newly allocated object op with its type and initial reference. Returns the initialized object. Other fields of the object are not initialized. Despite its name, this function is unrelated to the object's :meth:~object.__init__ method (:c:member:~PyTypeObject.tp_init slot). Specifically, this function does not call the object's :meth:!__init__ method.

In general, consider this function to be a low-level routine. Use :c:member:~PyTypeObject.tp_alloc where possible. For implementing :c:member:!tp_alloc for your type, prefer :c:func:PyType_GenericAlloc or :c:func:PyObject_New.

.. note::

  This function only initializes the object's memory corresponding to the
  initial :c:type:`PyObject` structure.  It does not zero the rest.

.. c:function:: PyVarObject* PyObject_InitVar(PyVarObject *op, PyTypeObject *type, Py_ssize_t size)

This does everything :c:func:PyObject_Init does, and also initializes the length information for a variable-size object.

.. note::

  This function only initializes some of the object's memory.  It does not
  zero the rest.

.. c:macro:: PyObject_New(TYPE, typeobj)

Allocates a new Python object using the C structure type TYPE and the Python type object typeobj (PyTypeObject*) by calling :c:func:PyObject_Malloc to allocate memory and initializing it like :c:func:PyObject_Init. The caller will own the only reference to the object (i.e. its reference count will be one).

Avoid calling this directly to allocate memory for an object; call the type's :c:member:~PyTypeObject.tp_alloc slot instead.

When populating a type's :c:member:~PyTypeObject.tp_alloc slot, :c:func:PyType_GenericAlloc is preferred over a custom function that simply calls this macro.

This macro does not call :c:member:~PyTypeObject.tp_alloc, :c:member:~PyTypeObject.tp_new (:meth:~object.__new__), or :c:member:~PyTypeObject.tp_init (:meth:~object.__init__).

This cannot be used for objects with :c:macro:Py_TPFLAGS_HAVE_GC set in :c:member:~PyTypeObject.tp_flags; use :c:macro:PyObject_GC_New instead.

Memory allocated by this macro must be freed with :c:func:PyObject_Free (usually called via the object's :c:member:~PyTypeObject.tp_free slot).

.. note::

  The returned memory is not guaranteed to have been completely zeroed
  before it was initialized.

.. note::

  This macro does not construct a fully initialized object of the given
  type; it merely allocates memory and prepares it for further
  initialization by :c:member:`~PyTypeObject.tp_init`.  To construct a
  fully initialized object, call *typeobj* instead.  For example::

     PyObject *foo = PyObject_CallNoArgs((PyObject *)&PyFoo_Type);

.. seealso::

  * :c:func:`PyObject_Free`
  * :c:macro:`PyObject_GC_New`
  * :c:func:`PyType_GenericAlloc`
  * :c:member:`~PyTypeObject.tp_alloc`

.. c:macro:: PyObject_NewVar(TYPE, typeobj, size)

Like :c:macro:PyObject_New except:

It allocates enough memory for the TYPE structure plus size (Py_ssize_t) fields of the size given by the :c:member:~PyTypeObject.tp_itemsize field of typeobj.
The memory is initialized like :c:func:PyObject_InitVar.

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.

Avoid calling this directly to allocate memory for an object; call the type's :c:member:~PyTypeObject.tp_alloc slot instead.

When populating a type's :c:member:~PyTypeObject.tp_alloc slot, :c:func:PyType_GenericAlloc is preferred over a custom function that simply calls this macro.

This cannot be used for objects with :c:macro:Py_TPFLAGS_HAVE_GC set in :c:member:~PyTypeObject.tp_flags; use :c:macro:PyObject_GC_NewVar instead.

Memory allocated by this function must be freed with :c:func:PyObject_Free (usually called via the object's :c:member:~PyTypeObject.tp_free slot).

.. note::

  The returned memory is not guaranteed to have been completely zeroed
  before it was initialized.

.. note::

  This macro does not construct a fully initialized object of the given
  type; it merely allocates memory and prepares it for further
  initialization by :c:member:`~PyTypeObject.tp_init`.  To construct a
  fully initialized object, call *typeobj* instead.  For example::

     PyObject *list_instance = PyObject_CallNoArgs((PyObject *)&PyList_Type);

.. seealso::

  * :c:func:`PyObject_Free`
  * :c:macro:`PyObject_GC_NewVar`
  * :c:func:`PyType_GenericAlloc`
  * :c:member:`~PyTypeObject.tp_alloc`

.. c:var:: PyObject _Py_NoneStruct

Object which is visible in Python as None. This should only be accessed using the :c:macro:Py_None macro, which evaluates to a pointer to this object.

.. seealso::

:ref:moduleobjects To allocate and create extension modules.

Deprecated aliases ^^^^^^^^^^^^^^^^^^

These are :term:soft deprecated aliases to existing functions and macros. They exist solely for backwards compatibility.

.. list-table:: :widths: auto :header-rows: 1

- Deprecated alias
- Function
- .. c:macro:: PyObject_NEW(type, typeobj)
- :c:macro:PyObject_New
- .. c:macro:: PyObject_NEW_VAR(type, typeobj, n)
- :c:macro:PyObject_NewVar
- .. c:macro:: PyObject_INIT(op, typeobj)
- :c:func:PyObject_Init
- .. c:macro:: PyObject_INIT_VAR(op, typeobj, n)
- :c:func:PyObject_InitVar
- .. c:macro:: PyObject_MALLOC(n)
- :c:func:PyObject_Malloc
- .. c:macro:: PyObject_REALLOC(p, n)
- :c:func:PyObject_Realloc
- .. c:macro:: PyObject_FREE(p)
- :c:func:PyObject_Free
- .. c:macro:: PyObject_DEL(p)
- :c:func:PyObject_Free
- .. c:macro:: PyObject_Del(p)
- :c:func:PyObject_Free