Allocating Objects on the Heap

Python documentation

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. 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.

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.

PyObject_New(TYPE, typeobj)

Allocate a new Python object using the C structure type TYPE and the Python type object typeobj (PyTypeObject*). Fields not defined by the Python object header are not initialized. The caller will own the only reference to the object (i.e. its reference count will be one). The size of the memory allocation is determined from the

tp_basicsize

field of the type object.

PyObject_NewVar(TYPE, typeobj, size)

Allocate a new Python object using the C structure type TYPE and the Python type object typeobj (PyTypeObject*). Fields not defined by the Python object header are not initialized. The allocated memory allows for the TYPE structure plus size (Py_ssize_t) fields of the size given by the

tp_itemsize

field of typeobj. 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.

voidPyObject_Del(void*op)

Releases memory allocated to an object using

PyObject_New

or

PyObject_NewVar

. This is normally called from the

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.

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.