The C structure of the objects used to describe built-in types.
This is the type object for type objects; it is the same object as
type in the Python layer.
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.
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.
Clear the internal lookup cache. Return the current version tag.
Changed in version 3.16: This function is now a no-op as the type cache is now implemented per-type. It still returns the current version tag.
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.
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.
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.
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.
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.
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.
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.
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.
Return non-zero if the type object o sets the feature feature. Type features are denoted by single bit flags.
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.
Return true if the type object includes support for the cycle detector; this
tests the type flag Py_TPFLAGS_HAVE_GC.
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.
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.
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.
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.
Return the type’s name. Equivalent to getting the type’s
__name__ attribute.
Added in version 3.11.
Return the type’s qualified name. Equivalent to getting the
type’s __qualname__ attribute.
Added in version 3.11.
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.
Return the type’s module name. Equivalent to getting the
type.__module__ attribute.
Added in version 3.13.
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.
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.
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.
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.
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.
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.
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.
Return true if instances of type support creating weak references, false
otherwise. This function always succeeds. type must not be NULL.
See also
The following function is used to create heap types:
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:
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.
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_nb_add to set PyNumberMethods.nb_add
The following slots need additional considerations when specified as slots:
Additional slots do not directly correspond to a PyTypeObject
struct field:
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_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:
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.
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.
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.
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.
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.
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.
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:
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.
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.
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.
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.
Slot ID that works like
Py_slot_subslots, except it specifies an array of
PyType_Slot structures.
Added in version 3.15.
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.
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 3.16.0a0 (unreleased): Prefer PyType_FromSlots() in new code.
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 3.16.0a0 (unreleased): Prefer PyType_FromSlots() in new code.
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 3.16.0a0 (unreleased): Prefer PyType_FromSlots() in new code.
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 3.16.0a0 (unreleased): Prefer PyType_FromSlots() in new code.
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.
Corresponds to Py_tp_name.
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.
Corresponds to Py_tp_itemsize.
Corresponds to Py_tp_flags.
Array of PyType_Slot (not PySlot) structures.
Terminated by the special slot value {0, NULL}.
Each slot ID should be specified at most once.
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).
Corresponds to PySlot.sl_id.
Corresponds to PySlot.sl_ptr.