Allocating Objects on the Heap

PyObject *_PyObject_New(PyTypeObject *type)
Return value: New reference.
PyVarObject *_PyObject_NewVar(PyTypeObject *type, Py_ssize_t size)
Return value: New reference.
PyObject *PyObject_Init(PyObject *op, PyTypeObject *type)
Return value: Borrowed reference. Part of the Stable ABI.

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 __init__() method (tp_init slot). Specifically, this function does not call the object’s __init__() method.

In general, consider this function to be a low-level routine. Use tp_alloc where possible. For implementing tp_alloc for your type, prefer PyType_GenericAlloc() or PyObject_New().

Note

This function only initializes the object’s memory corresponding to the initial PyObject structure. It does not zero the rest.

PyVarObject *PyObject_InitVar(PyVarObject *op, PyTypeObject *type, Py_ssize_t size)
Return value: Borrowed reference. Part of the Stable ABI.

This does everything 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.

PyObject_New(TYPE, typeobj)

Allocates a new Python object using the C structure type TYPE and the Python type object typeobj (PyTypeObject*) by calling PyObject_Malloc() to allocate memory and initializing it like 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 tp_alloc slot instead.

When populating a type’s tp_alloc slot, PyType_GenericAlloc() is preferred over a custom function that simply calls this macro.

This macro does not call tp_alloc, tp_new (__new__()), or tp_init (__init__()).

This cannot be used for objects with Py_TPFLAGS_HAVE_GC set in tp_flags; use PyObject_GC_New instead.

Memory allocated by this macro must be freed with PyObject_Free() (usually called via the object’s 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 tp_init. To construct a fully initialized object, call typeobj instead. For example:

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

See also

PyObject_NewVar(TYPE, typeobj, size)

Like PyObject_New except:

  • It allocates enough memory for the TYPE structure plus size (Py_ssize_t) fields of the size given by the tp_itemsize field of typeobj.

  • The memory is initialized like 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 tp_alloc slot instead.

When populating a type’s tp_alloc slot, PyType_GenericAlloc() is preferred over a custom function that simply calls this macro.

This cannot be used for objects with Py_TPFLAGS_HAVE_GC set in tp_flags; use PyObject_GC_NewVar instead.

Memory allocated by this function must be freed with PyObject_Free() (usually called via the object’s 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 tp_init. To construct a fully initialized object, call typeobj instead. For example:

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

See also

void PyObject_Del(void *op)

Same as PyObject_Free().

PyObject _Py_NoneStruct

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

See also

Module Objects

To allocate and create extension modules.