Type Objects

PyTypeObject

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

PyTypeObjectPyType_Type

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

intPyType_Check(PyObject *o)

Return non-zero if the objecto is a type object, including instances oftypes derived from the standard type object. Return 0 in all other cases.This function always succeeds.

intPyType_CheckExact(PyObject *o)

Return non-zero if the objecto is a type object, but not a subtype ofthe standard type object. Return 0 in all other cases. This functionalways succeeds.

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 non-zero if the type objecto sets the featurefeature.Type features are 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.

Note

If some of the base classes implements the GC protocol and the providedtype does not include thePy_TPFLAGS_HAVE_GC in its flags, thenthe GC protocol will be automatically implemented from its parents. Onthe contrary, if the type being created does includePy_TPFLAGS_HAVE_GC in its flags then itmust implement theGC protocol itself by at least implementing thetp_traverse handle.

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.

PyObject*PyType_GetModule(PyTypeObject *type)

Return the module object associated with the given type when the type wascreated usingPyType_FromModuleAndSpec().

If no module is associated with the given type, setsTypeErrorand returnsNULL.

This function is usually used to get the module in which a method is defined.Note that in such a method,PyType_GetModule(Py_TYPE(self))may not return the intended result.Py_TYPE(self) may be asubclass of the intended class, and subclassesare not necessarily defined in the same module as their superclass.SeePyCMethod to get the class that defines the method.

New in version 3.9.

void*PyType_GetModuleState(PyTypeObject *type)

Return the state of the module object associated with the given type.This is a shortcut for callingPyModule_GetState() on the resultofPyType_GetModule().

If no module is associated with the given type, setsTypeErrorand returnsNULL.

If thetype has an associated module but its state isNULL,returnsNULL without setting an exception.

New in version 3.9.

Creating Heap-Allocated Types

The following functions and structs are used to createheap types.

PyObject*PyType_FromModuleAndSpec(PyObject *module,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.

Themodule argument can be used to record the module in which the newclass is defined. It must be a module object orNULL.If notNULL, the module is associated with the new type and can later beretrieved withPyType_GetModule().The associated module is not inherited by subclasses; it must be specifiedfor each class individually.

This function callsPyType_Ready() on the new type.

New in version 3.9.

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

Equivalent toPyType_FromModuleAndSpec(NULL,spec,bases).

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 at all usingPyType_Spec andPyType_Slot:

The following fields cannot be set usingPyType_Spec andPyType_Slot under the limited API:

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

Changed in version 3.9:Slots inPyBufferProcs may be set in the unlimited API.

void *PyType_Slot.pfunc

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

May not beNULL.