Tuple Objects — Python documentation

Tuple Objects

type 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. This function always succeeds.

int PyTuple_CheckExact(PyObject *p)

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

PyObject *PyTuple_New(Py_ssize_t len)

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

PyObject *PyTuple_Pack(Py_ssize_t n, ...)

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

PyObject *PyTuple_GET_ITEM(PyObject *p, Py_ssize_t pos)

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

PyObject *PyTuple_GetSlice(PyObject *p, Py_ssize_t low, Py_ssize_t high)

Return the slice of the tuple pointed to by p between low and high, or NULL on failure. This is the equivalent of the Python expression p[low:high]. Indexing from the end of the list is not supported.

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. If pos is out of bounds, return -1 and set an IndexError exception.

Note

This function “steals” a reference to o and discards a reference to an item already in the tuple at the affected position.

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.

Note

This macro “steals” a reference to o, and, unlike PyTuple_SetItem(), does not discard a reference to any item that is being replaced; any reference in the tuple at position pos will be leaked.

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.

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.

New in version 3.4.

type PyStructSequence_Desc

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

Field	C Type	Meaning
name	const char *	name of the struct sequence type
doc	const 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)

type 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	Meaning
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

const char *const PyStructSequence_UnnamedField

Special value for a field name to leave it unnamed.

Changed in version 3.9: The type was changed from char *.

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.

Note

This function “steals” a reference to o.

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

Macro equivalent of PyStructSequence_SetItem().

Note

This function “steals” a reference to o.