typePyTypeObject
Part of the
(as an opaque struct).The C structure of the objects used to describe built-in types.
PyType_Type
Part of the
.This is the type object for type objects; it is the same object as
in the Python layer.
intPyType_Check(
*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.
intPyType_CheckExact(
*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.
unsignedintPyType_ClearCache()
Part of the
.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.
unsignedlongPyType_GetFlags(
*type)
Part of the
.Return the
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
.
Added in version 3.2.
Changed in version 3.4: The return type is now unsignedlong rather than long.
*PyType_GetDict(
*type)
Return the type object’s internal namespace, which is otherwise only exposed via a read-only proxy (
). This is a replacement for accessing
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
) 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.
voidPyType_Modified(
*type)
Part of the
.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.
intPyType_AddWatcher(
callback)
Register callback as a type watcher. Return a non-negative integer ID which must be passed to future calls to
. In case of error (e.g. no more watcher IDs available), return -1 and set an exception.
In free-threaded builds,
is not thread-safe, so it must be called at start up (before spawning the first thread).
Added in version 3.12.
intPyType_ClearWatcher(intwatcher_id)
Clear watcher identified by watcher_id (previously returned from
). 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
.
Added in version 3.12.
intPyType_Watch(intwatcher_id,
*type)
Mark type as watched. The callback granted watcher_id by
will be called whenever
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
.
Added in version 3.12.
Changed in version 3.15: The callback is now also invoked when a watched heap type is deallocated.
intPyType_Unwatch(intwatcher_id,
*type)
Mark type as not watched. This undoes a previous call to
. 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
.
On success, this function returns 0. On failure, this function returns -1 with an exception set.
Added in version 3.12.
typedefint(*PyType_WatchCallback)(
*type)
Type of a type-watcher callback function.
The callback must not modify type or cause
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.
intPyType_HasFeature(
*o, intfeature)
Return non-zero if the type object o sets the feature feature. Type features are denoted by single bit flags.
intPyType_FastSubclass(
*type, intflag)
Return non-zero if the type object type sets the subclass flag flag. Subclass flags are denoted by
. This function is used by many _Check functions for common types.
See also
, which is used as a slower alternative in _Check functions for types that don’t come with subclass flags.
intPyType_IS_GC(
*o)
Return true if the type object includes support for the cycle detector; this tests the type flag
.
intPyType_IsSubtype(
*a,
*b)
Part of the
.Return true if a is a subtype of b.
This function only checks for actual subtypes, which means that
is not called on b. Call
to do the same check that
would do.
*PyType_GenericAlloc(
*type,
nitems)
Return value: New reference. Part of the
.Generic handler for the
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
or
.
Do not call this directly to allocate memory for an object; call the type’s
slot instead.
For types that support garbage collection (i.e., the
flag is set), this function behaves like
or
(except the memory is guaranteed to be zeroed before initialization), and should be paired with
in
. Otherwise, it behaves like
or
(except the memory is guaranteed to be zeroed before initialization) and should be paired with
in tp_free.
*PyType_GenericNew(
*type,
*args,
*kwds)
Return value: New reference. Part of the
.Generic handler for the
slot of a type object. Creates a new instance using the type’s
slot and returns the resulting object.
intPyType_Ready(
*type)
Part of the
.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
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
handle.
*PyType_GetName(
*type)
Return value: New reference. Part of the
since version 3.11.Return the type’s name. Equivalent to getting the type’s
attribute.
Added in version 3.11.
*PyType_GetQualName(
*type)
Return value: New reference. Part of the
since version 3.11.Return the type’s qualified name. Equivalent to getting the type’s
attribute.
Added in version 3.11.
*PyType_GetFullyQualifiedName(
*type)
Part of the
since version 3.13.Return the type’s fully qualified name. Equivalent to f"{type.__module__}.{type.__qualname__}", or
if
is not a string or is equal to "builtins".
Added in version 3.13.
*PyType_GetModuleName(
*type)
Part of the
since version 3.13.Return the type’s module name. Equivalent to getting the
attribute.
Added in version 3.13.
void*PyType_GetSlot(
*type, intslot)
Part of the
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
for possible values of the slot argument.
Added in version 3.4.
Changed in version 3.10:
can now accept all types. Previously, it was limited to
.
*PyType_GetModule(
*type)
Return value: Borrowed reference. Part of the
since version 3.10.Return the module object associated with the given type when the type was created using
.
The returned reference is
from type, and will be valid as long as you hold a reference to type. Do not release it with
or similar.
If no module is associated with the given type, sets
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
to get the class that defines the method. See
for cases when PyCMethod cannot be used.
Added in version 3.9.
void*PyType_GetModuleState(
*type)
Part of the
since version 3.10.Return the state of the module object associated with the given type. This is a shortcut for calling
on the result of
.
If no module is associated with the given type, sets
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.
*PyType_GetModuleByToken(
*type, constvoid*mod_token)
Return value: New reference. Part of the
since version 3.15.Find the first superclass whose module has the given
, and return that module.
If no module is found, raises a
and returns NULL.
This function is intended to be used together with
to get module state from slot methods (such as
or
) and other places where a method’s defining class cannot be passed using the
calling convention.
Added in version 3.15.
*PyType_GetModuleByDef(
*type, struct
*def)
Return value: Borrowed reference. Part of the
since version 3.13.Find the first superclass whose module was created from the given
def, or whose
is equal to def, and return that module.
Note that modules created from a
always have their token set to the PyModuleDef’s address. In other words, this function is equivalent to
, 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
from type, and will be valid as long as you hold a reference to type. Do not release it with
or similar.
Added in version 3.11.
intPyType_GetBaseByToken(
*type, void*tp_token,
**result)
Part of the
since version 3.14.Find the first superclass in type’s
whose
token is equal to tp_token.
If found, set *result to a new
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.
intPyUnstable_Type_AssignVersionTag(
*type)
This is
. 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.
intPyType_SUPPORTS_WEAKREFS(
*type)
Return true if instances of type support creating weak references, false otherwise. This function always succeeds. type must not be NULL.
Creating Heap-Allocated Types
The following function is used to create
:
*PyType_FromSlots(const
*slots)
Part of the
since version 3.15.Create and return a
from a PySlot array. See
for general information on slots, and
for slots specific to type creation.
This function calls
on the new type.
Note that this function does not fully match the behavior of calling
or using the
statement. With user-provided base types or metaclasses, prefer
type (or the metaclass) over PyType_From* functions. Specifically:
is not called on the new class (and it must be set to type.__new__).
is not called on the new class.
is not called on any bases.
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
,
and
require live Python objects. In this case, it is recommended to put such slots on the stack, and use
to refer to an array of static slots. For example:
staticconstPySlotmy_slots[]={PySlot_STATIC_DATA(Py_tp_name,"MyClass"),PySlot_FUNC(Py_tp_repr,my_repr_func),...PySlot_END};PyObject*make_my_class(PyObject*module){PySlotall_slots[]={PySlot_STATIC_DATA(Py_slot_subslots,my_slots),PySlot_DATA(Py_tp_module,module),PySlot_END};returnPyType_FromSlots(all_slots);}Heap types created without the
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:
intPyType_Freeze(
*type)
Part of the
since version 3.14.Make a type immutable: set the
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
,
,
,
and
with an added Py_ prefix. For example, use:
to set
to set
to set
The following slots need additional considerations when specified as slots:
and
Additional slots do not directly correspond to a PyTypeObject struct field:
The following “offset” fields cannot be set using
:
(use
instead if possible)
(use
instead if possible)
(use "__vectorcalloffset__" in
)
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
. See
for details.
The following internal fields cannot be set at all when creating a heap type:
,
,
,
, and
.
The
slot is equivalent to
; 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:
(for clarity, prefer
rather than NULL)
Changed in version 3.9: Slots in
may be set in the unlimited API.
Changed in version 3.14: The field
can now be set using
. See the field’s documentation for details.
Changed in version 3.15: The
slot may be set to a single type object, making it equivalent to the
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
since version 3.15.
for the name of the type, used to set
.
This slot (or
) is required to create a type.
This may not be used in
. Use
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
since version 3.15.
for the size of the instance in bytes. It is used to set
.
The value must be positive.
This may not be used in
. Use
instead.
This slot may not be used with
. Use
instead if needed, but be aware that a type’s size is often considered an implementation detail.
Added in version 3.15.
Part of the
since version 3.15.
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
. Python will insert padding as needed to meet tp_basicsize’s alignment requirements.
Use
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
and Py_tp_extra_basicsize is an error.
This may not be used in
. Use negative
instead.
This slot may not be used with
.
Added in version 3.15.
Py_tp_itemsize
Part of the
since version 3.15.
for the size of one element of a variable-size type, in bytes. Used to set
. See tp_itemsize documentation for caveats.
The value must be positive.
If this slot is missing,
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
is zero).
The requested
is positive, suggesting that the memory layout of the base class is known.
The requested
is zero, suggesting that the subclass does not access the instance’s memory directly.
With the
flag.
This may not be used in
. Use
instead.
This slot may not be used with
.
Added in version 3.15.
Py_tp_flags
Part of the
since version 3.15.
for type flags, used to set
.
The Py_TPFLAGS_HEAPTYPE flag is not set,
sets it automatically.
This may not be used in
. Use negative
instead.
This slot may not be used with
. Use
instead.
Added in version 3.15.
Py_tp_bases
Part of the
.
for type flags, used to set
.
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
.
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
.Equivalent to
(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.
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
since version 3.15.
for the metaclass used to construct the resulting type object. When omitted the metaclass is derived from bases (
or the bases argument of
).
Metaclasses that override
are not supported, except if tp_new is NULL.
This may not be used in
. Use
to specify a metaclass with PyType_Spec.
This slot may not be used with
. Use
on the type object instead.
Added in version 3.15.
Py_tp_module
Part of the
since version 3.15.
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
. The associated module is not inherited by subclasses; it must be specified for each class individually.
This may not be used in
. Use
to specify a module with PyType_Spec.
This slot may not be used with
. Use
instead.
Added in version 3.15.
Py_tp_token
Part of the
since version 3.14.
for recording a static memory layout ID for a class.
If the class is defined using a
, and that spec is statically allocated, the token can be set to the spec using the special value
:
staticPyType_Slotfoo_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
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
with Py_tp_token.
Added in version 3.14.
Py_TP_USE_SPEC
Part of the
since version 3.14.Used as a value with
to set the token to the class’s
. May only be used for classes defined using PyType_Spec.
Expands to NULL.
Added in version 3.14.
Py_tp_slots
Part of the
since version 3.15.
that works like
, except it specifies an array of
structures.
Added in version 3.15.
Soft-deprecated API
The following functions are
. They will continue to work, but new features will be added as slots for
, not as arguments to new PyType_From* functions.
*PyType_FromMetaclass(
*metaclass,
*module,
*spec,
*bases)
Part of the
since version 3.12.Create and return a
from the spec (see
).
A non-NULLmetaclass argument corresponds to the
slot.
A non-NULLbases argument corresponds to the
slot, and takes precedence over Py_tp_bases and Py_tp_bases slots.
A non-NULLmodule argument corresponds to the
slot.
This function calls
on the new type.
Note that this function does not fully match the behavior of calling
or using the
statement. See the note in
documentation for details.
Added in version 3.12.
*PyType_FromModuleAndSpec(
*module,
*spec,
*bases)
Return value: New reference. Part of the
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
instances were returned.
The
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
is no longer allowed.
*PyType_FromSpecWithBases(
*spec,
*bases)
Return value: New reference. Part of the
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
instances were returned.
The
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
is no longer allowed.
*PyType_FromSpec(
*spec)
Return value: New reference. Part of the
.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
instances were returned.
The
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
is no longer allowed.
typePyType_Spec
Part of the
(including all members).Structure defining a type’s behavior, used for soft-deprecated functions like
.
This structure contains several members that can instead be specified as
for
, and an array of slot entries with a simpler structure.
constchar*name
Corresponds to
.
intbasicsize
If positive, corresponds to
.
If negative, corresponds to
set to the absolute value.
Changed in version 3.12: Previously, this field could not be negative.
intitemsize
Corresponds to
.
unsignedintflags
Corresponds to
.
*slots
Array of
(not
) structures.
Terminated by the special slot value {0,NULL}. Each slot ID should be specified at most once.
typePyType_Slot
Part of the
(including all members).Structure defining optional functionality of a type, used for soft-deprecated functions like
.
Note that a PyType_Slot array may be included in a PySlot array using
, and vice versa using
.
Each PyType_Slot structure tpslot is interpreted as the following
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
), or if this flag is present on the “parent” Py_tp_slots slot (if any).
intslot
Corresponds to
.
void*pfunc
Corresponds to
.