Type Objects

PyTypeObject

The C structure of the objects used to describe built-in types.

PyObject*PyType_Type

This is the type object for type objects; it is the same object astype in the Python layer.

intPyType_Check(PyObject *o)

Return true if the objecto is a type object, including instances of typesderived from the standard type object. Return false in all other cases.

intPyType_CheckExact(PyObject *o)

Return true if the objecto is a type object, but not a subtype of thestandard type object. Return false in all other cases.

unsigned intPyType_ClearCache()

Clear the internal lookup cache. Return the current version tag.

unsigned longPyType_GetFlags(PyTypeObject* type)

Return thetp_flags member oftype. This function is primarilymeant for use withPy_LIMITED_API; the individual flag bits areguaranteed to be stable across Python releases, but access totp_flags itself is not part of the limited API.

New in version 3.2.

Changed in version 3.4:The return type is nowunsignedlong rather thanlong.

voidPyType_Modified(PyTypeObject *type)

Invalidate the internal lookup cache for the type and all of itssubtypes. This function must be called after any manualmodification of the attributes or base classes of the type.

intPyType_HasFeature(PyTypeObject *o, int feature)

Return true if the type objecto sets the featurefeature. Type featuresare denoted by single bit flags.

intPyType_IS_GC(PyTypeObject *o)

Return true if the type object includes support for the cycle detector; thistests the type flagPy_TPFLAGS_HAVE_GC.

intPyType_IsSubtype(PyTypeObject *a,PyTypeObject *b)

Return true ifa is a subtype ofb.

This function only checks for actual subtypes, which means that__subclasscheck__() is not called onb. CallPyObject_IsSubclass() to do the same check thatissubclass()would do.

PyObject*PyType_GenericAlloc(PyTypeObject *type, Py_ssize_t nitems)
Return value: New reference.

Generic handler for thetp_alloc slot of a type object. UsePython’s default memory allocation mechanism to allocate a new instance andinitialize all its contents toNULL.

PyObject*PyType_GenericNew(PyTypeObject *type,PyObject *args,PyObject *kwds)
Return value: New reference.

Generic handler for thetp_new slot of a type object. Create anew instance using the type’stp_alloc slot.

intPyType_Ready(PyTypeObject *type)

Finalize a type object. This should be called on all type objects to finishtheir initialization. This function is responsible for adding inherited slotsfrom a type’s base class. Return0 on success, or return-1 and sets anexception on error.

void*PyType_GetSlot(PyTypeObject *type, int slot)

Return the function pointer stored in the given slot. If theresult isNULL, this indicates that either the slot isNULL,or that the function was called with invalid parameters.Callers will typically cast the result pointer into the appropriatefunction type.

SeePyType_Slot.slot for possible values of theslot argument.

An exception is raised iftype is not a heap type.

New in version 3.4.

Creating Heap-Allocated Types

The following functions and structs are used to createheap types.

PyObject*PyType_FromSpecWithBases(PyType_Spec *spec,PyObject *bases)
Return value: New reference.

Creates and returns a heap type object from thespec(Py_TPFLAGS_HEAPTYPE).

Ifbases is a tuple, the created heap type contains all types containedin it as base types.

Ifbases isNULL, thePy_tp_bases slot is used instead.If that also isNULL, thePy_tp_base slot is used instead.If that also isNULL, the new type derives fromobject.

This function callsPyType_Ready() on the new type.

New in version 3.3.

PyObject*PyType_FromSpec(PyType_Spec *spec)
Return value: New reference.

Equivalent toPyType_FromSpecWithBases(spec,NULL).

PyType_Spec

Structure defining a type’s behavior.

const char*PyType_Spec.name

Name of the type, used to setPyTypeObject.tp_name.

intPyType_Spec.basicsize
intPyType_Spec.itemsize

Size of the instance in bytes, used to setPyTypeObject.tp_basicsize andPyTypeObject.tp_itemsize.

intPyType_Spec.flags

Type flags, used to setPyTypeObject.tp_flags.

If thePy_TPFLAGS_HEAPTYPE flag is not set,PyType_FromSpecWithBases() sets it automatically.

PyType_Slot *PyType_Spec.slots

Array ofPyType_Slot structures.Terminated by the special slot value{0,NULL}.

PyType_Slot

Structure defining optional functionality of a type, containing a slot IDand a value pointer.

intPyType_Slot.slot

A slot ID.

Slot IDs are named like the field names of the structuresPyTypeObject,PyNumberMethods,PySequenceMethods,PyMappingMethods andPyAsyncMethods with an addedPy_ prefix.For example, use:

The following fields cannot be set usingPyType_Spec andPyType_Slot:

SettingPy_tp_bases orPy_tp_base may beproblematic on some platforms.To avoid issues, use thebases argument ofPyType_FromSpecWithBases() instead.

void *PyType_Slot.pfunc

The desired value of the slot. In most cases, this is a pointerto a function.

May not beNULL.