Python 3.6.5 Documentation >  Tuple Objects

Tuple Objects
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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.

Note: 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.

Note: 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
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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.

PyStructSequence_Desc

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

+---------------------+--------------------------------+--------------------------------------+
| Field | C Type | Meaning |
+=====================+================================+======================================+
| "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 | Meaning |
+=============+=================+========================================+
| "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.

Note: This function “steals” a reference to *o*.

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

Macro equivalent of "PyStructSequence_SetItem()".

Note: This function “steals” a reference to *o*.