Tuple Objects

Python documentation

typePyTupleObject

This subtype of

PyObject

represents a Python tuple object.

PyTypeObject

PyTuple_Type

Part of the

Stable ABI

.This instance of

PyTypeObject

represents the Python tuple type; it is the same object as

tuple

in the Python layer.

intPyTuple_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.

intPyTuple_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 value: New reference. Part of the

Stable ABI

. Thread safety:

Atomic

.Return a new tuple object of size len, or NULL with an exception set on failure.

PyObject

*PyTuple_FromArray(

PyObject

*const*array,

Py_ssize_t

size)

Thread safety:

Atomic

.Create a tuple of size items and copy references from array to the new tuple.

array can be NULL if size is 0.

On success, return a new reference. On error, set an exception and return NULL.

Added in version 3.15.

PyObject

*PyTuple_Pack(

Py_ssize_t

n, ...)

Return value: New reference. Part of the

Stable ABI

. Thread safety:

Atomic

.Return a new tuple object of size n, or NULL with an exception set 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)

Part of the

Stable ABI

. Thread safety:

Atomic

.Take a pointer to a tuple object, and return the size of that tuple. On error, return -1 with an exception set.

Py_ssize_t

PyTuple_GET_SIZE(

PyObject

*p)

Thread safety:

Atomic

.Like

PyTuple_Size()

, but without error checking.

PyObject

*PyTuple_GetItem(

PyObject

*p,

Py_ssize_t

pos)

Return value: Borrowed reference. Part of the

Stable ABI

. Thread safety:

Safe to call from multiple threads with external synchronization only

.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.

The returned reference is borrowed from the tuple p (that is: it is only valid as long as you hold a reference to p). To get a

strong reference

, use

Py_NewRef(PyTuple_GetItem(...))

or

PySequence_GetItem()

.

PyObject

*PyTuple_GET_ITEM(

PyObject

*p,

Py_ssize_t

pos)

Return value: Borrowed reference. Thread safety:

Safe to call from multiple threads with external synchronization only

.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. Part of the

Stable ABI

. Thread safety:

Atomic

.Return the slice of the tuple pointed to by p between low and high, or NULL with an exception set on failure.

This is the equivalent of the Python expression p[low:high]. Indexing from the end of the tuple is not supported.

intPyTuple_SetItem(

PyObject

*p,

Py_ssize_t

pos,

PyObject

*o)

Part of the

Stable ABI

. Thread safety:

Safe to call from multiple threads with external synchronization only

.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. This function should only be used to fill in brand new tuples; using it on an existing tuple is thread-unsafe.

Note

This function “

steals

” a reference to o and discards a reference to an item already in the tuple at the affected position (unless it was NULL).

voidPyTuple_SET_ITEM(

PyObject

*p,

Py_ssize_t

pos,

PyObject

*o)

Thread safety:

Safe to call from multiple threads with external synchronization only

.Like

PyTuple_SetItem()

, but does no error checking, and should only be used to fill in brand new tuples, using it on an existing tuple is thread-unsafe.

Bounds checking is performed as an assertion if Python is built in

debug mode

or

with assertions

.

Note

This function “

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.

Warning

This macro should only be used on tuples that are newly created. Using this macro on a tuple that is already in use (or in other words, has a refcount > 1) could lead to undefined behavior.

int_PyTuple_Resize(

PyObject

**p,

Py_ssize_t

newsize)

Thread safety:

Safe to call from multiple threads with external synchronization only

.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

A struct sequence object is a

named tuple

, that is, a sequence whose items can also be accessed through attributes. It is similar to

collections.namedtuple()

, but provides a slightly different interface.

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. Part of the

Stable ABI

. Thread safety:

Atomic

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

PyStructSequence_New()

.

Return NULL with an exception set on failure.

voidPyStructSequence_InitType(

PyTypeObject

*type,

PyStructSequence_Desc

*desc)

Thread safety:

Safe to call without external synchronization on distinct objects

.Initializes a struct sequence type type from desc in place.

intPyStructSequence_InitType2(

PyTypeObject

*type,

PyStructSequence_Desc

*desc)

Thread safety:

Safe to call without external synchronization on distinct objects

.Like

PyStructSequence_InitType()

, but returns 0 on success and -1 with an exception set on failure.

Added in version 3.4.

typePyStructSequence_Desc

Part of the

Stable ABI

(including all members).Contains the meta information of a struct sequence type to create.

constchar*name

Fully qualified name of the type; null-terminated UTF-8 encoded. The name must contain the module name.

constchar*doc

Pointer to docstring for the type or NULL to omit.

PyStructSequence_Field

*fields

Pointer to NULL-terminated array with field names of the new type.

intn_in_sequence

Number of fields visible to the Python side (if used as tuple).

typePyStructSequence_Field

Part of the

Stable ABI

(including all members).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.

constchar*name

Name for the field or NULL to end the list of named fields, set to

PyStructSequence_UnnamedField

to leave unnamed.

constchar*doc

Field docstring or NULL to omit.

constchar*constPyStructSequence_UnnamedField

Part of the

Stable ABI

since version 3.11.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)

Return value: New reference. Part of the

Stable ABI

. Thread safety:

Atomic

.Creates an instance of type, which must have been created with

PyStructSequence_NewType()

.

Return NULL with an exception set on failure.

PyObject

*PyStructSequence_GetItem(

PyObject

*p,

Py_ssize_t

pos)

Return value: Borrowed reference. Part of the

Stable ABI

. Thread safety:

Safe to call from multiple threads with external synchronization only

.Return the object at position pos in the struct sequence pointed to by p. The returned reference is borrowed from the struct sequence p (that is: it is only valid as long as you hold a reference to p).

Bounds checking is performed as an assertion if Python is built in

debug mode

or

with assertions

.

PyObject

*PyStructSequence_GET_ITEM(

PyObject

*p,

Py_ssize_t

pos)

Return value: Borrowed reference. Thread safety:

Safe to call from multiple threads with external synchronization only

.Alias to

PyStructSequence_GetItem()

.

Changed in version 3.13: Now implemented as an alias to

PyStructSequence_GetItem()

.

voidPyStructSequence_SetItem(

PyObject

*p,

Py_ssize_t

pos,

PyObject

*o)

Part of the

Stable ABI

. Thread safety:

Safe to call from multiple threads with external synchronization only

.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.

Bounds checking is performed as an assertion if Python is built in

debug mode

or

with assertions

.

Note

This function “

steals

” a reference to o.

voidPyStructSequence_SET_ITEM(

PyObject

*p,

Py_ssize_t

*pos,

PyObject

*o)

Thread safety:

Safe to call from multiple threads with external synchronization only

.Alias to

PyStructSequence_SetItem()

.

Changed in version 3.13: Now implemented as an alias to

PyStructSequence_SetItem()

.