# Tuple Objects

`PyTupleObject`

  This subtype of `PyObject` represents a Python tuple object.

PyTypeObject `PyTuple_Type`

  This instance of `PyTypeObject` represents the Python tuple type; it is the same object as `tuple` in the Python layer.

int `PyTuple_Check`(PyObject *p)

  Return true if p is a tuple object or an instance of a subtype of the tuple type.

int `PyTuple_CheckExact`(PyObject *p)

  Return true if p is a tuple object, but not an instance of a subtype of the tuple type.

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)

  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`

  Contains the meta information of a struct sequence type to create.

  Field | C Type | 意义
  --- | --- | ---
  `name` | `char *` | name of the struct sequence type
  `doc` | `char *` | pointer to docstring for the type or NULL to omit
  `fields` | `PyStructSequence_Field *` | pointer to NULL-terminated array with field names of the new type
  `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 Type | 意义
  --- | --- | ---
  `name` | `char *` | name for the field or NULL to end the list of named fields, set to PyStructSequence_UnnamedField to leave unnamed
  `doc` | `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)

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

PyObject* `PyStructSequence_GetItem`(PyObject *p, Py_ssize_t pos)

  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)

  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.

PyObject* `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.