# 元组对象

`PyTupleObject`

  这个 `PyObject` 的子类型代表一个 Python 的元组对象。

PyTypeObject `PyTuple_Type`

  `PyTypeObject` 的实例代表一个 Python 元组类型，这与 Python 层面的 `tuple` 是相同的对象。

int `PyTuple_Check`(PyObject *p)

  如果 p 是一个元组对象或者元组类型的子类型的实例，则返回真值。

int `PyTuple_CheckExact`(PyObject *p)

  如果 p 是一个元组对象，而不是一个元组子类型的实例，则返回真值。

PyObject* `PyTuple_New`(Py_ssize_t len)
  Return value: New reference.

  Return a new tuple object of size len, or NULL on failure.

PyObject* `PyTuple_Pack`(Py_ssize_t n, ...)
  Return value: New reference.

  Return a new tuple object of size n, or NULL on failure. The tuple values are initialized to the subsequent n C arguments pointing to Python objects. `PyTuple_Pack(2, a, b)` is equivalent to `Py_BuildValue("(OO)", a, b)`.

Py_ssize_t `PyTuple_Size`(PyObject *p)

  Take a pointer to a tuple object, and return the size of that tuple.

Py_ssize_t `PyTuple_GET_SIZE`(PyObject *p)

  Return the size of the tuple p, which must be non-NULL and point to a tuple; no error checking is performed.

PyObject* `PyTuple_GetItem`(PyObject *p, Py_ssize_t pos)
  Return value: Borrowed reference.

  Return the object at position pos in the tuple pointed to by p. If pos is out of bounds, return NULL and sets an `IndexError` exception.

PyObject* `PyTuple_GET_ITEM`(PyObject *p, Py_ssize_t pos)
  Return value: Borrowed reference.

  Like `PyTuple_GetItem()`, but does no checking of its arguments.

PyObject* `PyTuple_GetSlice`(PyObject *p, Py_ssize_t low, Py_ssize_t high)
  Return value: New reference.

  Take a slice of the tuple pointed to by p from low to high and return it as a new tuple.

int `PyTuple_SetItem`(PyObject *p, Py_ssize_t pos, PyObject *o)

  Insert a reference to object o at position pos of the tuple pointed to by p. Return `0` on success.

  注解

  This function "steals" a reference to o.

void `PyTuple_SET_ITEM`(PyObject *p, Py_ssize_t pos, PyObject *o)

  Like `PyTuple_SetItem()`, but does no error checking, and should only be used to fill in brand new tuples.

  注解

  This function "steals" a reference to o.

int `_PyTuple_Resize`(PyObject **p, Py_ssize_t newsize)

  Can be used to resize a tuple. newsize will be the new length of the tuple. Because tuples are supposed to be immutable, this should only be used if there is only one reference to the object. Do not use this if the tuple may already be known to some other part of the code. The tuple will always grow or shrink at the end. Think of this as destroying the old tuple and creating a new one, only more efficiently. Returns `0` on success. Client code should never assume that the resulting value of `*p` will be the same as before calling this function. If the object referenced by `*p` is replaced, the original `*p` is destroyed. On failure, returns `-1` and sets `*p` to NULL, and raises `MemoryError` or `SystemError`.

int `PyTuple_ClearFreeList`()

  Clear the free list. Return the total number of freed items.

# Struct Sequence Objects

Struct sequence objects are the C equivalent of `namedtuple()` objects, i.e. a sequence whose items can also be accessed through attributes. To create a struct sequence, you first have to create a specific struct sequence type.

PyTypeObject* `PyStructSequence_NewType`(PyStructSequence_Desc *desc)
  Return value: New reference.

  Create a new struct sequence type from the data in desc, described below. Instances of the resulting type can be created with `PyStructSequence_New()`.

void `PyStructSequence_InitType`(PyTypeObject *type, PyStructSequence_Desc *desc)

  Initializes a struct sequence type type from desc in place.

int `PyStructSequence_InitType2`(PyTypeObject *type, PyStructSequence_Desc *desc)

  The same as `PyStructSequence_InitType`, but returns `0` on success and `-1` on failure.

  3.4 新版功能.

`PyStructSequence_Desc`

  包含要创建的结构序列类型的元信息。

  Field | C 类型 | 意义
  --- | --- | ---
  `name` | `const char *` | 结构序列类型的名称
  `doc` | `const char *` | pointer to docstring for the type or NULL to omit
  `fields` | `PyStructSequence_Field *` | 指向以NULL结尾的数组的指针，其字段名称为新类型
  `n_in_sequence` | `int` | number of fields visible to the Python side (if used as tuple)

`PyStructSequence_Field`

  Describes a field of a struct sequence. As a struct sequence is modeled as a tuple, all fields are typed as `PyObject*`. The index in the `fields` array of the `PyStructSequence_Desc` determines which field of the struct sequence is described.

  Field | C 类型 | 意义
  --- | --- | ---
  `name` | `const char *` | name for the field or NULL to end the list of named fields, set to PyStructSequence_UnnamedField to leave unnamed
  `doc` | `const char *` | field docstring or NULL to omit

char* `PyStructSequence_UnnamedField`

  Special value for a field name to leave it unnamed.

PyObject* `PyStructSequence_New`(PyTypeObject *type)
  Return value: New reference.

  Creates an instance of type, which must have been created with `PyStructSequence_NewType()`.

PyObject* `PyStructSequence_GetItem`(PyObject *p, Py_ssize_t pos)
  Return value: Borrowed reference.

  Return the object at position pos in the struct sequence pointed to by p. No bounds checking is performed.

PyObject* `PyStructSequence_GET_ITEM`(PyObject *p, Py_ssize_t pos)
  Return value: Borrowed reference.

  Macro equivalent of `PyStructSequence_GetItem()`.

void `PyStructSequence_SetItem`(PyObject *p, Py_ssize_t pos, PyObject *o)

  Sets the field at index pos of the struct sequence p to value o. Like `PyTuple_SET_ITEM()`, this should only be used to fill in brand new instances.

  注解

  This function "steals" a reference to o.

void `PyStructSequence_SET_ITEM`(PyObject *p, Py_ssize_t *pos, PyObject *o)

  Macro equivalent of `PyStructSequence_SetItem()`.

  注解

  This function "steals" a reference to o.