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.
- 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 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 toPy_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.
- Return the object at position pos in the tuple pointed to by p. If pos is out of bounds, return
NULL
and set an IndexError exception.
- Like PyTuple_GetItem(), but does no checking of its arguments.
- 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 expressionp[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
toNULL
, 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 returns0
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 omitfields
PyStructSequence_Field *
pointer to
NULL
-terminated array with field names of the new typen_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 unnameddoc
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)
- Creates an instance of type, which must have been created with PyStructSequence_NewType().
- Return the object at position pos in the struct sequence pointed to by p. No bounds checking is performed.
- 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.