# Descriptor Objects

“Descriptors” are objects that describe some attribute of an object. They are found in the dictionary of type objects.

PyObject *PyDescr_NewGetSet(PyTypeObject *type, struct PyGetSetDef *getset)
  Return value: New reference. Part of the Stable ABI.

  Create a new get-set descriptor for extension type type from the `PyGetSetDef` structure getset.

  Get-set descriptors expose attributes implemented by C getter and setter functions rather than stored directly in the instance. This is the same kind of descriptor created for entries in `tp_getset`, and it appears in Python as a `types.GetSetDescriptorType` object.

  On success, return a strong reference to the descriptor. Return `NULL` with an exception set on failure.

PyObject *PyDescr_NewMember(PyTypeObject *type, struct PyMemberDef *member)
  Return value: New reference. Part of the Stable ABI.

  Create a new member descriptor for extension type type from the `PyMemberDef` structure member.

  Member descriptors expose fields in the type’s C struct as Python attributes. This is the same kind of descriptor created for entries in `tp_members`, and it appears in Python as a `types.MemberDescriptorType` object.

  On success, return a strong reference to the descriptor. Return `NULL` with an exception set on failure.

PyTypeObject PyMemberDescr_Type
  Part of the Stable ABI.

  The type object for member descriptor objects created from `PyMemberDef` structures. These descriptors expose fields of a C struct as attributes on a type, and correspond to `types.MemberDescriptorType` objects in Python.

PyTypeObject PyGetSetDescr_Type
  Part of the Stable ABI.

  The type object for get/set descriptor objects created from `PyGetSetDef` structures. These descriptors implement attributes whose value is computed by C getter and setter functions, and are used for many built-in type attributes. They correspond to `types.GetSetDescriptorType` objects in Python.

PyObject *PyDescr_NewMethod(PyTypeObject *type, struct PyMethodDef *meth)
  Return value: New reference. Part of the Stable ABI.

  Create a new method descriptor for extension type type from the `PyMethodDef` structure meth.

  Method descriptors expose C functions as methods on a type. This is the same kind of descriptor created for entries in `tp_methods`, and it appears in Python as a `types.MethodDescriptorType` object.

  On success, return a strong reference to the descriptor. Return `NULL` with an exception set on failure.

PyTypeObject PyMethodDescr_Type
  Part of the Stable ABI.

  The type object for method descriptor objects created from `PyMethodDef` structures. These descriptors expose C functions as methods on a type, and correspond to `types.MethodDescriptorType` objects in Python.

struct wrapperbase

  Describes a slot wrapper used by `PyDescr_NewWrapper()`.

  Each `wrapperbase` record stores the Python-visible name and metadata for a special method implemented by a type slot, together with the wrapper function used to adapt that slot to Python’s calling convention.

PyObject *PyDescr_NewWrapper(PyTypeObject *type, struct wrapperbase *base, void *wrapped)
  Return value: New reference.

  Create a new wrapper descriptor for extension type type from the `wrapperbase` structure base and the wrapped slot function pointer wrapped.

  Wrapper descriptors expose special methods implemented by type slots. This is the same kind of descriptor that CPython creates for slot-based special methods such as `__repr__` or `__add__`, and it appears in Python as a `types.WrapperDescriptorType` object.

  On success, return a strong reference to the descriptor. Return `NULL` with an exception set on failure.

PyTypeObject PyWrapperDescr_Type
  Part of the Stable ABI.

  The type object for wrapper descriptor objects created by `PyDescr_NewWrapper()` and `PyWrapper_New()`. Wrapper descriptors are used internally to expose special methods implemented via wrapper structures, and appear in Python as `types.WrapperDescriptorType` objects.

PyObject *PyDescr_NewClassMethod(PyTypeObject *type, PyMethodDef *method)
  Return value: New reference. Part of the Stable ABI.

  Create a new class method descriptor for extension type type from the `PyMethodDef` structure method.

  Class method descriptors expose C methods that receive the class rather than an instance when accessed. This is the same kind of descriptor created for `METH_CLASS` entries in `tp_methods`, and it appears in Python as a `types.ClassMethodDescriptorType` object.

  On success, return a strong reference to the descriptor. Return `NULL` with an exception set on failure.

int PyDescr_IsData(PyObject *descr)

  Return non-zero if the descriptor object descr describes a data attribute, or `0` if it describes a method. descr must be a descriptor object; there is no error checking.

PyObject *PyWrapper_New(PyObject *d, PyObject *self)
  Return value: New reference. Part of the Stable ABI.

  Create a new bound wrapper object from the wrapper descriptor d and the instance self.

  This is the bound form of a wrapper descriptor created by `PyDescr_NewWrapper()`. CPython creates these objects when a slot wrapper is accessed through an instance, and they appear in Python as `types.MethodWrapperType` objects.

  On success, return a strong reference to the wrapper object. Return `NULL` with an exception set on failure.

PyDescr_COMMON

  This is a soft deprecated macro including the common fields for a descriptor object.

  This was included in Python’s C API by mistake; do not use it in extensions. For creating custom descriptor objects, create a class implementing the descriptor protocol (`tp_descr_get` and `tp_descr_set`).

## Built-in descriptors

PyTypeObject PyProperty_Type
  Part of the Stable ABI.

  The type object for property objects. This is the same object as `property` in the Python layer.

PyTypeObject PySuper_Type
  Part of the Stable ABI.

  The type object for super objects. This is the same object as `super` in the Python layer.

PyTypeObject PyClassMethod_Type

  The type of class method objects. This is the same object as `classmethod` in the Python layer.

PyTypeObject PyClassMethodDescr_Type
  Part of the Stable ABI.

  The type object for C-level class method descriptor objects. This is the type of the descriptors created for `classmethod()` defined in C extension types, and corresponds to `types.ClassMethodDescriptorType` objects in Python.

PyObject *PyClassMethod_New(PyObject *callable)

  Create a new `classmethod` object wrapping callable. callable must be a callable object and must not be `NULL`.

  On success, this function returns a strong reference to a new class method descriptor. On failure, this function returns `NULL` with an exception set.

PyTypeObject PyStaticMethod_Type

  The type of static method objects. This is the same object as `staticmethod` in the Python layer.

PyObject *PyStaticMethod_New(PyObject *callable)

  Create a new `staticmethod` object wrapping callable. callable must be a callable object and must not be `NULL`.

  On success, this function returns a strong reference to a new static method descriptor. On failure, this function returns `NULL` with an exception set.