型別物件
********

type PyTypeObject
    * 為 受限 API 的一部分 （做為一個不透明結構 (opaque struct)）.*

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

PyTypeObject PyType_Type
    * 為 穩定 ABI 的一部分.*

   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()
    * 為 穩定 ABI 的一部分.*

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

unsigned long PyType_GetFlags(PyTypeObject *type)
    * 為 穩定 ABI 的一部分.*

   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.

   在 3.2 版被加入.

   在 3.4 版的變更: 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.

   在 3.12 版被加入.

void PyType_Modified(PyTypeObject *type)
    * 為 穩定 ABI 的一部分.*

   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).

   在 3.12 版被加入.

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()".

   在 3.12 版被加入.

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.)

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

   在 3.12 版被加入.

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()".

   成功時此函式會回傳 "0"。失敗時此函式回傳 "-1" 並設定例外。

   在 3.12 版被加入.

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.

   在 3.12 版被加入.

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.

   也參考:

     "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)
    * 為 穩定 ABI 的一部分.*

   如果 *a* 是 *b* 的子類別則回傳 true。

   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)
    *回傳值：新的參照。** 為 穩定 ABI 的一部分.*

   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)
    *回傳值：新的參照。** 為 穩定 ABI 的一部分.*

   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)
    * 為 穩定 ABI 的一部分.*

   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.

   備註:

     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)
    *回傳值：新的參照。** 為 穩定 ABI 的一部分 自 3.11 版本開始.*

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

   在 3.11 版被加入.

PyObject *PyType_GetQualName(PyTypeObject *type)
    *回傳值：新的參照。** 為 穩定 ABI 的一部分 自 3.11 版本開始.*

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

   在 3.11 版被加入.

PyObject *PyType_GetFullyQualifiedName(PyTypeObject *type)
    * 為 穩定 ABI 的一部分 自 3.13 版本開始.*

   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"".

   在 3.13 版被加入.

PyObject *PyType_GetModuleName(PyTypeObject *type)
    * 為 穩定 ABI 的一部分 自 3.13 版本開始.*

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

   在 3.13 版被加入.

void *PyType_GetSlot(PyTypeObject *type, int slot)
    * 為 穩定 ABI 的一部分 自 3.4 版本開始.*

   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.

   在 3.4 版被加入.

   在 3.10 版的變更: "PyType_GetSlot()" can now accept all types.
   Previously, it was limited to heap types.

PyObject *PyType_GetModule(PyTypeObject *type)
    * 為 穩定 ABI 的一部分 自 3.10 版本開始.*

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

   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_GetModuleByDef()" for cases when "PyCMethod"
   cannot be used.

   在 3.9 版被加入.

void *PyType_GetModuleState(PyTypeObject *type)
    * 為 穩定 ABI 的一部分 自 3.10 版本開始.*

   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.

   在 3.9 版被加入.

PyObject *PyType_GetModuleByDef(PyTypeObject *type, struct PyModuleDef *def)
    *回傳值：借用參照。** 為 穩定 ABI 的一部分 自 3.13 版本開始.*

   Find the first superclass whose module was created from the given
   "PyModuleDef" *def*, 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.

   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.

   在 3.11 版被加入.

int PyType_GetBaseByToken(PyTypeObject *type, void *token, PyTypeObject **result)
    * 為 穩定 ABI 的一部分 自 3.14 版本開始.*

   Find the first superclass in *type*'s *method resolution order*
   whose "Py_tp_token" token is equal to the given one.

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

   * 如果沒找到，則將 **result* 設為 "NULL" 並回傳 "0"。

   * 在發生錯誤時，將 **result* 設為 "NULL" 並回傳 "-1"，同時設定例外
     。

   如果 *result* 引數為 "NULL"，則不會設定 **result*。如果你只需要回傳
   值，請使用此選項。

   *token* 引數不可為 "NULL"。

   在 3.14 版被加入.

int PyUnstable_Type_AssignVersionTag(PyTypeObject *type)

   *這是 不穩定 API，它可能在小版本發布中沒有任何警告地被變更。*

   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.

   在 3.12 版被加入.

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".

   也參考:

     * 弱參照物件

     * "weakref"


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

The following functions and structs are used to create heap types.

PyObject *PyType_FromMetaclass(PyTypeObject *metaclass, PyObject *module, PyType_Spec *spec, PyObject *bases)
    * 為 穩定 ABI 的一部分 自 3.12 版本開始.*

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

   The metaclass *metaclass* is used to construct the resulting type
   object. When *metaclass* is "NULL", the metaclass is derived from
   *bases* (or *Py_tp_base[s]* slots if *bases* is "NULL", see below).

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

   The *bases* argument can be used to specify base classes; it can
   either be only one class or a tuple of classes. If *bases* is
   "NULL", the "Py_tp_bases" slot is used instead. If that also is
   "NULL", the "Py_tp_base" slot is used instead. If that also is
   "NULL", the new type derives from "object".

   The *module* argument can be used to record the module in which the
   new class is defined. It must be a module object or "NULL". If not
   "NULL", 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 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__()" 不會在新類別上被呼叫（且它必須被設為 "type.__new__"）
     。

   * "__init__()" 不會在新類別上被呼叫。

   * "__init_subclass__()" 不會在任何基底上被呼叫。

   * "__set_name__()" 不會在新的描述器上被呼叫。

   在 3.12 版被加入.

PyObject *PyType_FromModuleAndSpec(PyObject *module, PyType_Spec *spec, PyObject *bases)
    *回傳值：新的參照。** 為 穩定 ABI 的一部分 自 3.10 版本開始.*

   等價於 "PyType_FromMetaclass(NULL, module, spec, bases)"。

   在 3.9 版被加入.

   在 3.10 版的變更: The function now accepts a single class as the
   *bases* argument and "NULL" as the "tp_doc" slot.

   在 3.12 版的變更: 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.

   在 3.14 版的變更: Creating classes whose metaclass overrides
   "tp_new" is no longer allowed.

PyObject *PyType_FromSpecWithBases(PyType_Spec *spec, PyObject *bases)
    *回傳值：新的參照。** 為 穩定 ABI 的一部分 自 3.3 版本開始.*

   等價於 "PyType_FromMetaclass(NULL, NULL, spec, bases)"。

   在 3.3 版被加入.

   在 3.12 版的變更: 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.

   在 3.14 版的變更: Creating classes whose metaclass overrides
   "tp_new" is no longer allowed.

PyObject *PyType_FromSpec(PyType_Spec *spec)
    *回傳值：新的參照。** 為 穩定 ABI 的一部分.*

   等價於 "PyType_FromMetaclass(NULL, NULL, spec, NULL)"。

   在 3.12 版的變更: 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.

   在 3.14 版的變更: Creating classes whose metaclass overrides
   "tp_new" is no longer allowed.

int PyType_Freeze(PyTypeObject *type)
    * 為 穩定 ABI 的一部分 自 3.14 版本開始.*

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

   所有 *type* 的基底類別都必須是不可變的。

   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.

   在 3.14 版被加入.

type PyType_Spec
    * 為 穩定 ABI 的一部分 （包含所有成員）.*

   Structure defining a type's behavior.

   const char *name

      Name of the type, used to set "PyTypeObject.tp_name".

   int basicsize

      If positive, specifies the size of the instance in bytes. It is
      used to set "PyTypeObject.tp_basicsize".

      If zero, specifies that "tp_basicsize" should be inherited.

      If negative, the absolute value specifies how much space
      instances of the class need *in addition* to the superclass. Use
      "PyObject_GetTypeData()" to get a pointer to subclass-specific
      memory reserved this way. For negative "basicsize", Python will
      insert padding when needed to meet "tp_basicsize"'s alignment
      requirements.

      在 3.12 版的變更: 在過去此欄位不可為負值。

   int itemsize

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

      If zero, "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").

      * 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.

   unsigned int flags

      Type flags, used to set "PyTypeObject.tp_flags".

      如果未設定 "Py_TPFLAGS_HEAPTYPE" 旗標，則
      "PyType_FromSpecWithBases()" 會自動設定它。

   PyType_Slot *slots

      Array of "PyType_Slot" structures. Terminated by the special
      slot value "{0, NULL}".

      Each slot ID should be specified at most once.

type PyType_Slot
    * 為 穩定 ABI 的一部分 （包含所有成員）.*

   Structure defining optional functionality of a type, containing a
   slot ID and a value pointer.

   int 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" 以設定 "PyTypeObject.tp_dealloc"

      * "Py_nb_add" 以設定 "PyNumberMethods.nb_add"

      * "Py_sq_length" 以設定 "PySequenceMethods.sq_length"

      An additional slot is supported that does not correspond to a
      "PyTypeObject" struct field:

      * "Py_tp_token"

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

      * "tp_weaklistoffset"（如果可能，請改用
        "Py_TPFLAGS_MANAGED_WEAKREF"）

      * "tp_dictoffset"（如果可能，請改用 "Py_TPFLAGS_MANAGED_DICT"）

      * "tp_vectorcall_offset"（請用 PyMemberDef 中的
        ""__vectorcalloffset__""）

      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".

      Setting "Py_tp_bases" or "Py_tp_base" may be problematic on some
      platforms. To avoid issues, use the *bases* argument of
      "PyType_FromSpecWithBases()" instead.

      在 3.9 版的變更: Slots in "PyBufferProcs" may be set in the
      unlimited API.

      在 3.11 版的變更: "bf_getbuffer" and "bf_releasebuffer" are now
      available under the limited API.

      在 3.14 版的變更: The field "tp_vectorcall" can now be set using
      "Py_tp_vectorcall".  See the field's documentation for details.

   void *pfunc

      The desired value of the slot. In most cases, this is a pointer
      to a function.

      *pfunc* values may not be "NULL", except for the following
      slots:

      * "Py_tp_doc"

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

Py_tp_token
    * 為 穩定 ABI 的一部分 自 3.14 版本開始.*

   A "slot" that records a static memory layout ID for a class.

   If the "PyType_Spec" of the class 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".

   在 3.14 版被加入.

   Py_TP_USE_SPEC
       * 為 穩定 ABI 的一部分 自 3.14 版本開始.*

      Used as a value with "Py_tp_token" to set the token to the
      class's "PyType_Spec". Expands to "NULL".

      在 3.14 版被加入.
