Type Objects — Python documentation
Type Objects
- type 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 as type in the Python layer.
- int PyType_Check(PyObject *o)
- Return true if the object o is a type object, including instances of types derived from the standard type object. Return false in all other cases.
- int PyType_CheckExact(PyObject *o)
- Return true if the object o is a type object, but not a subtype of the standard type object. Return false in all other cases.
- unsigned int PyType_ClearCache()
- Clear the internal lookup cache. Return the current version tag.
- unsigned long PyType_GetFlags(PyTypeObject *type)
Return the tp_flags member of type. This function is primarily meant for use with Py_LIMITED_API; the individual flag bits are guaranteed to be stable across Python releases, but access to tp_flags itself is not part of the limited API.
New in version 3.2.
Changed in version 3.4: The return type is now
unsigned long
rather thanlong
.
- void PyType_Modified(PyTypeObject *type)
- Invalidate the internal lookup cache for the type and all of its subtypes. This function must be called after any manual modification of the attributes or base classes of the type.
- int PyType_HasFeature(PyTypeObject *o, int feature)
- Return true if the type object o sets the feature feature. Type features are denoted by single bit flags.
- int PyType_IS_GC(PyTypeObject *o)
- Return true if the type object includes support for the cycle detector; this tests the type flag Py_TPFLAGS_HAVE_GC.
- int PyType_IsSubtype(PyTypeObject *a, PyTypeObject *b)
Return true if a is a subtype of b.
This function only checks for actual subtypes, which means that __subclasscheck__() is not called on b. Call PyObject_IsSubclass() to do the same check that issubclass() would do.
- PyObject *PyType_GenericAlloc(PyTypeObject *type, Py_ssize_t nitems)
- Generic handler for the tp_alloc slot of a type object. Use Python’s default memory allocation mechanism to allocate a new instance and initialize all its contents to
NULL
.
- PyObject *PyType_GenericNew(PyTypeObject *type, PyObject *args, PyObject *kwds)
- Generic handler for the tp_new slot of a type object. Create a new instance using the type’s tp_alloc slot.
- int PyType_Ready(PyTypeObject *type)
- Finalize a type object. This should be called on all type objects to finish their initialization. This function is responsible for adding inherited slots from a type’s base class. Return
0
on success, or return-1
and sets an exception on error.
- void *PyType_GetSlot(PyTypeObject *type, int slot)
Return the function pointer stored in the given slot. If the result is
NULL
, 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 appropriate function type.See
PyType_Slot.slot
for possible values of the slot argument.An exception is raised if type is not a heap type.
New in version 3.4.
Creating Heap-Allocated Types
The following functions and structs are used to create heap types.
- PyObject *PyType_FromSpecWithBases(PyType_Spec *spec, PyObject *bases)
Creates and returns a heap type object from the spec (Py_TPFLAGS_HEAPTYPE).
If bases is a tuple, the created heap type contains all types contained in it as base types.
If bases is
NULL
, the Py_tp_bases slot is used instead. If that also isNULL
, the Py_tp_base slot is used instead. If that also isNULL
, the new type derives from object.This function calls PyType_Ready() on the new type.
New in version 3.3.
- PyObject *PyType_FromSpec(PyType_Spec *spec)
- Equivalent to
PyType_FromSpecWithBases(spec, NULL)
.
- type PyType_Spec
Structure defining a type’s behavior.
- const char *PyType_Spec.name
Name of the type, used to set PyTypeObject.tp_name.
- int PyType_Spec.basicsize
- int PyType_Spec.itemsize
Size of the instance in bytes, used to set PyTypeObject.tp_basicsize and PyTypeObject.tp_itemsize.
- int PyType_Spec.flags
Type flags, used to set PyTypeObject.tp_flags.
If the
Py_TPFLAGS_HEAPTYPE
flag is not set, PyType_FromSpecWithBases() sets it automatically.
- PyType_Slot *PyType_Spec.slots
Array of PyType_Slot structures. Terminated by the special slot value
{0, NULL}
.
- const char *PyType_Spec.name
- type PyType_Slot
Structure defining optional functionality of a type, containing a slot ID and a value pointer.
- int PyType_Slot.slot
A slot ID.
Slot IDs are named like the field names of the structures PyTypeObject, PyNumberMethods, PySequenceMethods, PyMappingMethods and PyAsyncMethods with an added
Py_
prefix. For example, use:Py_tp_dealloc
to set PyTypeObject.tp_deallocPy_nb_add
to set PyNumberMethods.nb_addPy_sq_length
to set PySequenceMethods.sq_length
The following fields cannot be set using PyType_Spec and
PyType_Slot
:tp_print
Setting
Py_tp_bases
orPy_tp_base
may be problematic on some platforms. To avoid issues, use the bases argument ofPyType_FromSpecWithBases()
instead.
- void *PyType_Slot.pfunc
The desired value of the slot. In most cases, this is a pointer to a function.
May not be
NULL
.
- int PyType_Slot.slot