Type Objects
************

type PyTypeObject
    * Part of the Stable ABI (as an opaque struct).*

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

PyTypeObject PyType_Type
    * Part of the Stable ABI.*

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

int PyType_CheckExact(PyObject *o)

   Return non-zero if the object *o* is a type object, but not a
   subtype of the standard type object.  Return 0 in all other cases.
   This function always succeeds.

unsigned int PyType_ClearCache()
    * Part of the Stable ABI.*

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

unsigned long PyType_GetFlags(PyTypeObject *type)
    * Part of the Stable ABI.*

   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.

   Added in version 3.2.

   Changed in version 3.4: The return type is now "unsigned long"
   rather than "long".

PyObject *PyType_GetDict(PyTypeObject *type)

   Return the type object’s internal namespace, which is otherwise
   only exposed via a read-only proxy ("cls.__dict__"). This is a
   replacement for accessing "tp_dict" directly. The returned
   dictionary must be treated as read-only.

   This function is meant for specific embedding and language-binding
   cases, where direct access to the dict is necessary and indirect
   access (e.g. via the proxy or "PyObject_GetAttr()") isn’t adequate.

   Extension modules should continue to use "tp_dict", directly or
   indirectly, when setting up their own types.

   Added in version 3.12.

void PyType_Modified(PyTypeObject *type)
    * Part of the Stable ABI.*

   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_AddWatcher(PyType_WatchCallback callback)

   Register *callback* as a type watcher. Return a non-negative
   integer ID which must be passed to future calls to
   "PyType_Watch()". In case of error (e.g. no more watcher IDs
   available), return "-1" and set an exception.

   In free-threaded builds, "PyType_AddWatcher()" is not thread-safe,
   so it must be called at start up (before spawning the first
   thread).

   Added in version 3.12.

int PyType_ClearWatcher(int watcher_id)

   Clear watcher identified by *watcher_id* (previously returned from
   "PyType_AddWatcher()"). Return "0" on success, "-1" on error (e.g.
   if *watcher_id* was never registered.)

   An extension should never call "PyType_ClearWatcher" with a
   *watcher_id* that was not returned to it by a previous call to
   "PyType_AddWatcher()".

   Added in version 3.12.

int PyType_Watch(int watcher_id, PyObject *type)

   Mark *type* as watched. The callback granted *watcher_id* by
   "PyType_AddWatcher()" will be called whenever "PyType_Modified()"
   reports a change to *type*. (The callback may be called only once
   for a series of consecutive modifications to *type*, if
   "_PyType_Lookup()" is not called on *type* between the
   modifications; this is an implementation detail and subject to
   change.)

   The callback is also invoked when a watched heap type is
   deallocated.

   An extension should never call "PyType_Watch" with a *watcher_id*
   that was not returned to it by a previous call to
   "PyType_AddWatcher()".

   Added in version 3.12.

   Changed in version 3.15: The callback is now also invoked when a
   watched heap type is deallocated.

int PyType_Unwatch(int watcher_id, PyObject *type)

   Mark *type* as not watched. This undoes a previous call to
   "PyType_Watch()". *type* must not be "NULL".

   An extension should never call this function with a *watcher_id*
   that was not returned to it by a previous call to
   "PyType_AddWatcher()".

   On success, this function returns "0". On failure, this function
   returns "-1" with an exception set.

   Added in version 3.12.

typedef int (*PyType_WatchCallback)(PyObject *type)

   Type of a type-watcher callback function.

   The callback must not modify *type* or cause "PyType_Modified()" to
   be called on *type* or any type in its MRO; violating this rule
   could cause infinite recursion.

   The callback may be called during type deallocation. In this case,
   the type object is temporarily resurrected (its reference count is
   at least 1) and all its attributes are still valid. However, the
   callback should not store new strong references to the type, as
   this would resurrect the object and prevent its deallocation.

   Added in version 3.12.

   Changed in version 3.15: The callback may now be called during
   deallocation of a watched heap type.

int PyType_HasFeature(PyTypeObject *o, int feature)

   Return non-zero if the type object *o* sets the feature *feature*.
   Type features are denoted by single bit flags.

int PyType_FastSubclass(PyTypeObject *type, int flag)

   Return non-zero if the type object *type* sets the subclass flag
   *flag*. Subclass flags are denoted by "Py_TPFLAGS_*_SUBCLASS". This
   function is used by many "_Check" functions for common types.

   See also:

     "PyObject_TypeCheck()", which is used as a slower alternative in
     "_Check" functions for types that don’t come with subclass 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)
    * Part of the Stable ABI.*

   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)
    *Return value: New reference.** Part of the Stable ABI.*

   Generic handler for the "tp_alloc" slot of a type object.  Uses
   Python’s default memory allocation mechanism to allocate memory for
   a new instance, zeros the memory, then initializes the memory as if
   by calling "PyObject_Init()" or "PyObject_InitVar()".

   Do not call this directly to allocate memory for an object; call
   the type’s "tp_alloc" slot instead.

   For types that support garbage collection (i.e., the
   "Py_TPFLAGS_HAVE_GC" flag is set), this function behaves like
   "PyObject_GC_New" or "PyObject_GC_NewVar" (except the memory is
   guaranteed to be zeroed before initialization), and should be
   paired with "PyObject_GC_Del()" in "tp_free". Otherwise, it behaves
   like "PyObject_New" or "PyObject_NewVar" (except the memory is
   guaranteed to be zeroed before initialization) and should be paired
   with "PyObject_Free()" in "tp_free".

PyObject *PyType_GenericNew(PyTypeObject *type, PyObject *args, PyObject *kwds)
    *Return value: New reference.** Part of the Stable ABI.*

   Generic handler for the "tp_new" slot of a type object.  Creates a
   new instance using the type’s "tp_alloc" slot and returns the
   resulting object.

int PyType_Ready(PyTypeObject *type)
    * Part of the Stable ABI.*

   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.

   Note:

     If some of the base classes implements the GC protocol and the
     provided type does not include the "Py_TPFLAGS_HAVE_GC" in its
     flags, then the GC protocol will be automatically implemented
     from its parents. On the contrary, if the type being created does
     include "Py_TPFLAGS_HAVE_GC" in its flags then it **must**
     implement the GC protocol itself by at least implementing the
     "tp_traverse" handle.

PyObject *PyType_GetName(PyTypeObject *type)
    *Return value: New reference.** Part of the Stable ABI since
   version 3.11.*

   Return the type’s name. Equivalent to getting the type’s "__name__"
   attribute.

   Added in version 3.11.

PyObject *PyType_GetQualName(PyTypeObject *type)
    *Return value: New reference.** Part of the Stable ABI since
   version 3.11.*

   Return the type’s qualified name. Equivalent to getting the type’s
   "__qualname__" attribute.

   Added in version 3.11.

PyObject *PyType_GetFullyQualifiedName(PyTypeObject *type)
    * Part of the Stable ABI since version 3.13.*

   Return the type’s fully qualified name. Equivalent to
   "f"{type.__module__}.{type.__qualname__}"", or "type.__qualname__"
   if "type.__module__" is not a string or is equal to ""builtins"".

   Added in version 3.13.

PyObject *PyType_GetModuleName(PyTypeObject *type)
    * Part of the Stable ABI since version 3.13.*

   Return the type’s module name. Equivalent to getting the
   "type.__module__" attribute.

   Added in version 3.13.

void *PyType_GetSlot(PyTypeObject *type, int slot)
    * Part of the Stable ABI since version 3.4.*

   Return the function pointer stored in the given slot. If the result
   is "NULL", this indicates that either the slot is "NULL", 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.

   Added in version 3.4.

   Changed in version 3.10: "PyType_GetSlot()" can now accept all
   types. Previously, it was limited to heap types.

PyObject *PyType_GetModule(PyTypeObject *type)
    *Return value: Borrowed reference.** Part of the Stable ABI since
   version 3.10.*

   Return the module object associated with the given type when the
   type was created using "PyType_FromModuleAndSpec()".

   The returned reference is *borrowed* from *type*, and will be valid
   as long as you hold a reference to *type*. Do not release it with
   "Py_DECREF()" or similar.

   If no module is associated with the given type, sets "TypeError"
   and returns "NULL".

   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 a *subclass* of the intended class,
   and subclasses are not necessarily defined in the same module as
   their superclass. See "PyCMethod" to get the class that defines the
   method. See "PyType_GetModuleByToken()" for cases when "PyCMethod"
   cannot be used.

   Added in version 3.9.

void *PyType_GetModuleState(PyTypeObject *type)
    * Part of the Stable ABI since version 3.10.*

   Return the state of the module object associated with the given
   type. This is a shortcut for calling "PyModule_GetState()" on the
   result of "PyType_GetModule()".

   If no module is associated with the given type, sets "TypeError"
   and returns "NULL".

   If the *type* has an associated module but its state is "NULL",
   returns "NULL" without setting an exception.

   Added in version 3.9.

PyObject *PyType_GetModuleByToken(PyTypeObject *type, const void *mod_token)
    *Return value: New reference.** Part of the Stable ABI since
   version 3.15.*

   Find the first superclass whose module has the given module token,
   and return that module.

   If no module is found, raises a "TypeError" and returns "NULL".

   This function is intended to be used together with
   "PyModule_GetState()" to get module state from slot methods (such
   as "tp_init" or "nb_add") and other places where a method’s
   defining class cannot be passed using the "PyCMethod" calling
   convention.

   Added in version 3.15.

PyObject *PyType_GetModuleByDef(PyTypeObject *type, struct PyModuleDef *def)
    *Return value: Borrowed reference.** Part of the Stable ABI since
   version 3.13.*

   Find the first superclass whose module was created from the given
   "PyModuleDef" *def*, or whose module token is equal to *def*, and
   return that module.

   Note that modules created from a "PyModuleDef" always have their
   token set to the "PyModuleDef"’s address. In other words, this
   function is equivalent to "PyType_GetModuleByToken()", except that
   it:

   * returns a borrowed reference, and

   * has a non-"void*" argument type (which is a cosmetic difference
     in C).

   The returned reference is *borrowed* from *type*, and will be valid
   as long as you hold a reference to *type*. Do not release it with
   "Py_DECREF()" or similar.

   Added in version 3.11.

int PyType_GetBaseByToken(PyTypeObject *type, void *tp_token, PyTypeObject **result)
    * Part of the Stable ABI since version 3.14.*

   Find the first superclass in *type*’s *method resolution order*
   whose "Py_tp_token" token is equal to *tp_token*.

   * If found, set **result* to a new *strong reference* to it and
     return "1".

   * If not found, set **result* to "NULL" and return "0".

   * On error, set **result* to "NULL" and return "-1" with an
     exception set.

   The *result* argument may be "NULL", in which case **result* is not
   set. Use this if you need only the return value.

   The *tp_token* argument may not be "NULL".

   Added in version 3.14.

int PyUnstable_Type_AssignVersionTag(PyTypeObject *type)

   *This is Unstable API. It may change without warning in minor
   releases.*

   Attempt to assign a version tag to the given type.

   Returns 1 if the type already had a valid version tag or a new one
   was assigned, or 0 if a new tag could not be assigned.

   Added in version 3.12.

int PyType_SUPPORTS_WEAKREFS(PyTypeObject *type)

   Return true if instances of *type* support creating weak
   references, false otherwise. This function always succeeds. *type*
   must not be "NULL".

   See also:

     * Weak Reference Objects

     * "weakref"


Creating Heap-Allocated Types
=============================

The following function is used to create heap types:

PyObject *PyType_FromSlots(const PySlot *slots)
    * Part of the Stable ABI since version 3.15.*

   Create and return a heap type from a "PySlot" array. See Definition
   slots for general information on slots, and Type slot IDs for slots
   specific to type creation.

   This function calls "PyType_Ready()" on the new type.

   Note that this function does *not* fully match the behavior of
   calling "type()" or using the "class" statement. With user-provided
   base types or metaclasses, prefer calling "type" (or the metaclass)
   over "PyType_From*" functions. Specifically:

   * "__new__()" is not called on the new class (and it must be set to
     "type.__new__").

   * "__init__()" is not called on the new class.

   * "__init_subclass__()" is not called on any bases.

   * "__set_name__()" is not called on new descriptors.

   Slots are typically defined as a global static constant arrays.
   However, sometimes slot values are not statically known at compile
   time. For example, slots like "Py_tp_bases", "Py_tp_metaclass" and
   "Py_tp_module" require live Python objects. In this case, it is
   recommended to put such slots on the stack, and use
   "Py_slot_subslots" to refer to an array of static slots. For
   example:

      static const PySlot my_slots[] = {
         PySlot_STATIC_DATA(Py_tp_name, "MyClass"),
         PySlot_FUNC(Py_tp_repr, my_repr_func),
         ...
         PySlot_END
      };

      PyObject *make_my_class(PyObject *module) {
         PySlot all_slots[] = {
            PySlot_STATIC_DATA(Py_slot_subslots, my_slots),
            PySlot_DATA(Py_tp_module, module),
            PySlot_END
         };
         return PyType_FromSlots(all_slots);
      }

Heap types created without the "Py_TPFLAGS_IMMUTABLETYPE" flag may be
modified, for example by setting attributes on them, as with classes
defined in Python code. Sometimes, such modifications are necessary to
fully initialize a type, but you may wish to prevent users from
changing the type after the initialization is done:

int PyType_Freeze(PyTypeObject *type)
    * Part of the Stable ABI since version 3.14.*

   Make a type immutable: set the "Py_TPFLAGS_IMMUTABLETYPE" flag.

   All base classes of *type* must be immutable.

   On success, return "0". On error, set an exception and return "-1".

   The type must not be used before it’s made immutable. For example,
   type instances must not be created before the type is made
   immutable.

   Added in version 3.14.


Type slot IDs
-------------

Most type 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_dealloc"

* "Py_nb_add" to set "PyNumberMethods.nb_add"

* "Py_sq_length" to set "PySequenceMethods.sq_length"

The following slots need additional considerations when specified as
slots:

* "Py_tp_name"

* "Py_tp_basicsize" and "Py_tp_extra_basicsize"

* "Py_tp_itemsize"

* "Py_tp_flags"

Additional slots do not directly correspond to a "PyTypeObject" struct
field:

* "Py_tp_token"

* "Py_tp_metaclass"

* "Py_tp_module"

The following “offset” fields cannot be set using "PyType_Slot":

* "tp_weaklistoffset" (use "Py_TPFLAGS_MANAGED_WEAKREF" instead if
  possible)

* "tp_dictoffset" (use "Py_TPFLAGS_MANAGED_DICT" instead if possible)

* "tp_vectorcall_offset" (use ""__vectorcalloffset__"" in PyMemberDef)

If it is not possible to switch to a "MANAGED" flag (for example, for
vectorcall or to support Python older than 3.12), specify the offset
in "Py_tp_members". See PyMemberDef documentation for details.

The following internal fields cannot be set at all when creating a
heap type:

* "tp_dict", "tp_mro", "tp_cache", "tp_subclasses", and "tp_weaklist".

The "Py_tp_base" slot is equivalent to "Py_tp_bases"; both may be set
either to a type or a tuple of types. If both are specified, the value
of "Py_tp_bases" is used.

Slot values may not be "NULL", except for the following:

* "Py_tp_doc"

* "Py_tp_token" (for clarity, prefer "Py_TP_USE_SPEC" rather than
  "NULL")

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

Changed in version 3.11: "bf_getbuffer" and "bf_releasebuffer" are now
available under the limited API.

Changed in version 3.14: The field "tp_vectorcall" can now be set
using "Py_tp_vectorcall".  See the field’s documentation for details.

Changed in version 3.15: The "Py_tp_bases" slot may be set to a single
type object, making it equivalent to the "Py_tp_base" slot.
Previously, a tuple of types was required.

The following slots correspond to fields in the underlying type
structure, but need extra remarks for use as slots:

Py_tp_name
    * Part of the Stable ABI since version 3.15.*

   "Slot ID" for the name of the type, used to set
   "PyTypeObject.tp_name".

   This slot (or "PyType_Spec.name") is required to create a type.

   This may not be used in "PyType_Spec.slots". Use "PyType_Spec.name"
   instead.

   **CPython implementation detail:** CPython processes slots in
   order. It is recommended to put "Py_tp_name" at the beginning of
   the slots array, so that if processing of a later slots fails,
   error messages can include the name.

   Added in version 3.15.

Py_tp_basicsize
    * Part of the Stable ABI since version 3.15.*

   "Slot ID" for the size of the instance in bytes. It is used to set
   "PyTypeObject.tp_basicsize".

   The value must be positive.

   This may not be used in "PyType_Spec.slots". Use
   "PyType_Spec.basicsize" instead.

   This slot may not be used with "PyType_GetSlot()". Use
   "PyTypeObject.tp_basicsize" instead if needed, but be aware that a
   type’s size is often considered an implementation detail.

   Added in version 3.15.

Py_tp_extra_basicsize
    * Part of the Stable ABI since version 3.15.*

   "Slot ID" for type data size in bytes, that is, how much space
   instances of the class need *in addition* to space needed for
   superclasses.

   The value is used, together with the size of superclasses, to set
   "PyTypeObject.tp_basicsize". Python will insert padding as needed
   to meet "tp_basicsize"’s alignment requirements.

   Use "PyObject_GetTypeData()" to get a pointer to subclass-specific
   memory reserved this way.

   The value must be positive. To specify that instances need no
   additional size (that is, size should be inherited), omit the
   "Py_tp_extra_basicsize" slot rather than set it to zero.

   Specifying both "Py_tp_basicsize" and "Py_tp_extra_basicsize" is an
   error.

   This may not be used in "PyType_Spec.slots". Use negative
   "PyType_Spec.basicsize" instead.

   This slot may not be used with "PyType_GetSlot()".

   Added in version 3.15.

Py_tp_itemsize
    * Part of the Stable ABI since version 3.15.*

   "Slot ID" for the size of one element of a variable-size type, in
   bytes. Used to set "PyTypeObject.tp_itemsize". See "tp_itemsize"
   documentation for caveats.

   The value must be positive.

   If this slot is missing, "tp_itemsize" is inherited. Extending
   arbitrary variable-sized classes is dangerous, since some types use
   a fixed offset for variable-sized memory, which can then overlap
   fixed-sized memory used by a subclass. To help prevent mistakes,
   inheriting "itemsize" is only possible in the following situations:

   * The base is not variable-sized (its "tp_itemsize" is zero).

   * The requested "PyType_Spec.basicsize" is positive, suggesting
     that the memory layout of the base class is known.

   * The requested "PyType_Spec.basicsize" is zero, suggesting that
     the subclass does not access the instance’s memory directly.

   * With the "Py_TPFLAGS_ITEMS_AT_END" flag.

   This may not be used in "PyType_Spec.slots". Use
   "PyType_Spec.itemsize" instead.

   This slot may not be used with "PyType_GetSlot()".

   Added in version 3.15.

Py_tp_flags
    * Part of the Stable ABI since version 3.15.*

   "Slot ID" for type flags, used to set "PyTypeObject.tp_flags".

   The "Py_TPFLAGS_HEAPTYPE" flag is not set,
   "PyType_FromSpecWithBases()" sets it automatically.

   This may not be used in "PyType_Spec.slots". Use negative
   "PyType_Spec.basicsize" instead.

   This slot may not be used with "PyType_GetSlot()". Use
   "PyType_GetFlags()" instead.

   Added in version 3.15.

Py_tp_bases
    * Part of the Stable ABI.*

   "Slot ID" for type flags, used to set "PyTypeObject.tp_bases".

   The slot can be set to a tuple of type objects which the newly
   created type should inherit from, like the “positional arguments”
   of a Python class definition.

   Alternately, the slot can be set to a single type object to specify
   a single base. The effect is the same as specifying a one-element
   tuple.

   Changed in version 3.15: Previously, "Py_tp_bases" required a tuple
   of types.

Py_tp_base
    * Part of the Stable ABI.*

   Equivalent to "Py_tp_bases" (with "s" at the end). If both are
   specified, "Py_tp_bases" takes priority and this slot is ignored.

   Changed in version 3.15: Previously, "Py_tp_base" required a single
   type, not a tuple.

   Soft deprecated since version 3.15: When not targeting older Python
   versions, prefer "Py_tp_bases".

The following slots do not correspond to public fields in the
underlying structures:

Py_tp_metaclass
    * Part of the Stable ABI since version 3.15.*

   "Slot ID" for the metaclass used to construct the resulting type
   object. When omitted the metaclass is derived from bases
   ("Py_tp_bases" or the *bases* argument of
   "PyType_FromMetaclass()").

   Metaclasses that override "tp_new" are not supported, except if
   "tp_new" is "NULL".

   This may not be used in "PyType_Spec.slots". Use
   "PyType_FromMetaclass()" to specify a metaclass with "PyType_Spec".

   This slot may not be used with "PyType_GetSlot()". Use "Py_TYPE()"
   on the type object instead.

   Added in version 3.15.

Py_tp_module
    * Part of the Stable ABI since version 3.15.*

   "Slot ID" for recording the module in which the new class is
   defined.

   The value must be a module object. The module is associated with
   the new type and can later be retrieved with "PyType_GetModule()".
   The associated module is not inherited by subclasses; it must be
   specified for each class individually.

   This may not be used in "PyType_Spec.slots". Use
   "PyType_FromMetaclass()" to specify a module with "PyType_Spec".

   This slot may not be used with "PyType_GetSlot()". Use
   "PyType_GetModule()" instead.

   Added in version 3.15.

Py_tp_token
    * Part of the Stable ABI since version 3.14.*

   "Slot ID" for recording a static memory layout ID for a class.

   If the class is defined using a "PyType_Spec", and that spec is
   statically allocated, the token can be set to the spec using the
   special value "Py_TP_USE_SPEC":

      static PyType_Slot foo_slots[] = {
         {Py_tp_token, Py_TP_USE_SPEC},

   It can also be set to an arbitrary pointer, but you must ensure
   that:

   * The pointer outlives the class, so it’s not reused for something
     else while the class exists.

   * It “belongs” to the extension module where the class lives, so it
     will not clash with other extensions.

   Use "PyType_GetBaseByToken()" to check if a class’s superclass has
   a given token – that is, check whether the memory layout is
   compatible.

   To get the token for a given class (without considering
   superclasses), use "PyType_GetSlot()" with "Py_tp_token".

   Added in version 3.14.

   Py_TP_USE_SPEC
       * Part of the Stable ABI since version 3.14.*

      Used as a value with "Py_tp_token" to set the token to the
      class’s "PyType_Spec". May only be used for classes defined
      using "PyType_Spec".

      Expands to "NULL".

      Added in version 3.14.

Py_tp_slots
    * Part of the Stable ABI since version 3.15.*

   "Slot ID" that works like "Py_slot_subslots", except it specifies
   an array of "PyType_Slot" structures.

   Added in version 3.15.


Soft-deprecated API
===================

The following functions are *soft deprecated*. They will continue to
work, but new features will be added as slots for
"PyType_FromSlots()", not as arguments to new "PyType_From*"
functions.

PyObject *PyType_FromMetaclass(PyTypeObject *metaclass, PyObject *module, PyType_Spec *spec, PyObject *bases)
    * Part of the Stable ABI since version 3.12.*

   Create and return a heap type from the *spec* (see
   "Py_TPFLAGS_HEAPTYPE").

   A non-"NULL" *metaclass* argument corresponds to the
   "Py_tp_metaclass" slot.

   A non-"NULL" *bases* argument corresponds to the "Py_tp_bases"
   slot, and takes precedence over "Py_tp_bases" and "Py_tp_bases"
   slots.

   A non-"NULL" *module* argument corresponds to the "Py_tp_module"
   slot.

   This function calls "PyType_Ready()" on the new type.

   Note that this function does *not* fully match the behavior of
   calling "type()" or using the "class" statement. See the note in
   "PyType_FromSlots()" documentation for details.

   Added in version 3.12.

   Soft deprecated since version 3.15.0rc1 (unreleased): Prefer
   "PyType_FromSlots()" in new code.

PyObject *PyType_FromModuleAndSpec(PyObject *module, PyType_Spec *spec, PyObject *bases)
    *Return value: New reference.** Part of the Stable ABI since
   version 3.10.*

   Equivalent to "PyType_FromMetaclass(NULL, module, spec, bases)".

   Added in version 3.9.

   Changed in version 3.10: The function now accepts a single class as
   the *bases* argument and "NULL" as the "tp_doc" slot.

   Changed in version 3.12: The function now finds and uses a
   metaclass corresponding to the provided base classes.  Previously,
   only "type" instances were returned.The "tp_new" of the metaclass
   is *ignored*. which may result in incomplete initialization.
   Creating classes whose metaclass overrides "tp_new" is deprecated.

   Changed in version 3.14: Creating classes whose metaclass overrides
   "tp_new" is no longer allowed.

   Soft deprecated since version 3.15.0rc1 (unreleased): Prefer
   "PyType_FromSlots()" in new code.

PyObject *PyType_FromSpecWithBases(PyType_Spec *spec, PyObject *bases)
    *Return value: New reference.** Part of the Stable ABI since
   version 3.3.*

   Equivalent to "PyType_FromMetaclass(NULL, NULL, spec, bases)".

   Added in version 3.3.

   Changed in version 3.12: The function now finds and uses a
   metaclass corresponding to the provided base classes.  Previously,
   only "type" instances were returned.The "tp_new" of the metaclass
   is *ignored*. which may result in incomplete initialization.
   Creating classes whose metaclass overrides "tp_new" is deprecated.

   Changed in version 3.14: Creating classes whose metaclass overrides
   "tp_new" is no longer allowed.

   Soft deprecated since version 3.15.0rc1 (unreleased): Prefer
   "PyType_FromSlots()" in new code.

PyObject *PyType_FromSpec(PyType_Spec *spec)
    *Return value: New reference.** Part of the Stable ABI.*

   Equivalent to "PyType_FromMetaclass(NULL, NULL, spec, NULL)".

   Changed in version 3.12: The function now finds and uses a
   metaclass corresponding to the base classes provided in
   *Py_tp_base[s]* slots. Previously, only "type" instances were
   returned.The "tp_new" of the metaclass is *ignored*. which may
   result in incomplete initialization. Creating classes whose
   metaclass overrides "tp_new" is deprecated.

   Changed in version 3.14: Creating classes whose metaclass overrides
   "tp_new" is no longer allowed.

   Soft deprecated since version 3.15.0rc1 (unreleased): Prefer
   "PyType_FromSlots()" in new code.

type PyType_Spec
    * Part of the Stable ABI (including all members).*

   Structure defining a type’s behavior, used for soft-deprecated
   functions like "PyType_FromMetaclass()".

   This structure contains several members that can instead be
   specified as slots for "PyType_FromSlots()", and an array of slot
   entries with a simpler structure.

   const char *name

      Corresponds to "Py_tp_name".

   int basicsize

      If positive, corresponds to "Py_tp_basicsize".

      If negative, corresponds to "Py_tp_extra_basicsize" set to the
      absolute value.

      Changed in version 3.12: Previously, this field could not be
      negative.

   int itemsize

      Corresponds to "Py_tp_itemsize".

   unsigned int flags

      Corresponds to "Py_tp_flags".

   PyType_Slot *slots

      Array of "PyType_Slot" (not "PySlot") structures.

      Terminated by the special slot value "{0, NULL}". Each slot ID
      should be specified at most once.

      type PyType_Slot
          * Part of the Stable ABI (including all members).*

         Structure defining optional functionality of a type, used for
         soft-deprecated functions like "PyType_FromMetaclass()".

         Note that a "PyType_Slot" array may be included in a "PySlot"
         array using "Py_tp_slots", and vice versa using
         "Py_slot_subslots".

         Each "PyType_Slot" structure "tpslot" is interpreted as the
         following "PySlot" structure:

            (PySlot){
               .sl_id=tpslot.slot,
               .sl_flags=PySlot_INTPTR | sub_static,
               .sl_ptr=tpslot.func
            }

         where "sub_static" is "PySlot_STATIC" if the slot requires
         the flag (such as for "Py_tp_methods"), or if this flag is
         present on the “parent” "Py_tp_slots" slot (if any).

         int slot

            Corresponds to "PySlot.sl_id".

         void *pfunc

            Corresponds to "PySlot.sl_ptr".
