cpython/Doc/c-api/long.rst
Antonio Cuni 315fc52db1
bpo-42528: Improve the docs of most Py*_Check{,Exact} API calls (GH-23602)
I think that none of these API calls can fail, but only few of them are
documented as such. Add the sentence "This function always succeeds" (which is
the same already used e.g. by PyNumber_Check) to all of them.
2021-01-06 12:38:26 +01:00

320 lines
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ReStructuredText

.. highlight:: c
.. _longobjects:
Integer Objects
---------------
.. index:: object: long integer
object: integer
All integers are implemented as "long" integer objects of arbitrary size.
On error, most ``PyLong_As*`` APIs return ``(return type)-1`` which cannot be
distinguished from a number. Use :c:func:`PyErr_Occurred` to disambiguate.
.. c:type:: PyLongObject
This subtype of :c:type:`PyObject` represents a Python integer object.
.. c:var:: PyTypeObject PyLong_Type
This instance of :c:type:`PyTypeObject` represents the Python integer type.
This is the same object as :class:`int` in the Python layer.
.. c:function:: int PyLong_Check(PyObject *p)
Return true if its argument is a :c:type:`PyLongObject` or a subtype of
:c:type:`PyLongObject`. This function always succeeds.
.. c:function:: int PyLong_CheckExact(PyObject *p)
Return true if its argument is a :c:type:`PyLongObject`, but not a subtype of
:c:type:`PyLongObject`. This function always succeeds.
.. c:function:: PyObject* PyLong_FromLong(long v)
Return a new :c:type:`PyLongObject` object from *v*, or ``NULL`` on failure.
The current implementation keeps an array of integer objects for all integers
between ``-5`` and ``256``, when you create an int in that range you actually
just get back a reference to the existing object.
.. c:function:: PyObject* PyLong_FromUnsignedLong(unsigned long v)
Return a new :c:type:`PyLongObject` object from a C :c:type:`unsigned long`, or
``NULL`` on failure.
.. c:function:: PyObject* PyLong_FromSsize_t(Py_ssize_t v)
Return a new :c:type:`PyLongObject` object from a C :c:type:`Py_ssize_t`, or
``NULL`` on failure.
.. c:function:: PyObject* PyLong_FromSize_t(size_t v)
Return a new :c:type:`PyLongObject` object from a C :c:type:`size_t`, or
``NULL`` on failure.
.. c:function:: PyObject* PyLong_FromLongLong(long long v)
Return a new :c:type:`PyLongObject` object from a C :c:type:`long long`, or ``NULL``
on failure.
.. c:function:: PyObject* PyLong_FromUnsignedLongLong(unsigned long long v)
Return a new :c:type:`PyLongObject` object from a C :c:type:`unsigned long long`,
or ``NULL`` on failure.
.. c:function:: PyObject* PyLong_FromDouble(double v)
Return a new :c:type:`PyLongObject` object from the integer part of *v*, or
``NULL`` on failure.
.. c:function:: PyObject* PyLong_FromString(const char *str, char **pend, int base)
Return a new :c:type:`PyLongObject` based on the string value in *str*, which
is interpreted according to the radix in *base*. If *pend* is non-``NULL``,
*\*pend* will point to the first character in *str* which follows the
representation of the number. If *base* is ``0``, *str* is interpreted using
the :ref:`integers` definition; in this case, leading zeros in a
non-zero decimal number raises a :exc:`ValueError`. If *base* is not ``0``,
it must be between ``2`` and ``36``, inclusive. Leading spaces and single
underscores after a base specifier and between digits are ignored. If there
are no digits, :exc:`ValueError` will be raised.
.. c:function:: PyObject* PyLong_FromUnicodeObject(PyObject *u, int base)
Convert a sequence of Unicode digits in the string *u* to a Python integer
value.
.. versionadded:: 3.3
.. c:function:: PyObject* PyLong_FromVoidPtr(void *p)
Create a Python integer from the pointer *p*. The pointer value can be
retrieved from the resulting value using :c:func:`PyLong_AsVoidPtr`.
.. XXX alias PyLong_AS_LONG (for now)
.. c:function:: long PyLong_AsLong(PyObject *obj)
.. index::
single: LONG_MAX
single: OverflowError (built-in exception)
Return a C :c:type:`long` representation of *obj*. If *obj* is not an
instance of :c:type:`PyLongObject`, first call its :meth:`__index__` method
(if present) to convert it to a :c:type:`PyLongObject`.
Raise :exc:`OverflowError` if the value of *obj* is out of range for a
:c:type:`long`.
Returns ``-1`` on error. Use :c:func:`PyErr_Occurred` to disambiguate.
.. versionchanged:: 3.8
Use :meth:`__index__` if available.
.. versionchanged:: 3.10
This function will no longer use :meth:`__int__`.
.. c:function:: long PyLong_AsLongAndOverflow(PyObject *obj, int *overflow)
Return a C :c:type:`long` representation of *obj*. If *obj* is not an
instance of :c:type:`PyLongObject`, first call its :meth:`__index__`
method (if present) to convert it to a :c:type:`PyLongObject`.
If the value of *obj* is greater than :const:`LONG_MAX` or less than
:const:`LONG_MIN`, set *\*overflow* to ``1`` or ``-1``, respectively, and
return ``-1``; otherwise, set *\*overflow* to ``0``. If any other exception
occurs set *\*overflow* to ``0`` and return ``-1`` as usual.
Returns ``-1`` on error. Use :c:func:`PyErr_Occurred` to disambiguate.
.. versionchanged:: 3.8
Use :meth:`__index__` if available.
.. versionchanged:: 3.10
This function will no longer use :meth:`__int__`.
.. c:function:: long long PyLong_AsLongLong(PyObject *obj)
.. index::
single: OverflowError (built-in exception)
Return a C :c:type:`long long` representation of *obj*. If *obj* is not an
instance of :c:type:`PyLongObject`, first call its :meth:`__index__` method
(if present) to convert it to a :c:type:`PyLongObject`.
Raise :exc:`OverflowError` if the value of *obj* is out of range for a
:c:type:`long long`.
Returns ``-1`` on error. Use :c:func:`PyErr_Occurred` to disambiguate.
.. versionchanged:: 3.8
Use :meth:`__index__` if available.
.. versionchanged:: 3.10
This function will no longer use :meth:`__int__`.
.. c:function:: long long PyLong_AsLongLongAndOverflow(PyObject *obj, int *overflow)
Return a C :c:type:`long long` representation of *obj*. If *obj* is not an
instance of :c:type:`PyLongObject`, first call its :meth:`__index__` method
(if present) to convert it to a :c:type:`PyLongObject`.
If the value of *obj* is greater than :const:`LLONG_MAX` or less than
:const:`LLONG_MIN`, set *\*overflow* to ``1`` or ``-1``, respectively,
and return ``-1``; otherwise, set *\*overflow* to ``0``. If any other
exception occurs set *\*overflow* to ``0`` and return ``-1`` as usual.
Returns ``-1`` on error. Use :c:func:`PyErr_Occurred` to disambiguate.
.. versionadded:: 3.2
.. versionchanged:: 3.8
Use :meth:`__index__` if available.
.. versionchanged:: 3.10
This function will no longer use :meth:`__int__`.
.. c:function:: Py_ssize_t PyLong_AsSsize_t(PyObject *pylong)
.. index::
single: PY_SSIZE_T_MAX
single: OverflowError (built-in exception)
Return a C :c:type:`Py_ssize_t` representation of *pylong*. *pylong* must
be an instance of :c:type:`PyLongObject`.
Raise :exc:`OverflowError` if the value of *pylong* is out of range for a
:c:type:`Py_ssize_t`.
Returns ``-1`` on error. Use :c:func:`PyErr_Occurred` to disambiguate.
.. c:function:: unsigned long PyLong_AsUnsignedLong(PyObject *pylong)
.. index::
single: ULONG_MAX
single: OverflowError (built-in exception)
Return a C :c:type:`unsigned long` representation of *pylong*. *pylong*
must be an instance of :c:type:`PyLongObject`.
Raise :exc:`OverflowError` if the value of *pylong* is out of range for a
:c:type:`unsigned long`.
Returns ``(unsigned long)-1`` on error.
Use :c:func:`PyErr_Occurred` to disambiguate.
.. c:function:: size_t PyLong_AsSize_t(PyObject *pylong)
.. index::
single: SIZE_MAX
single: OverflowError (built-in exception)
Return a C :c:type:`size_t` representation of *pylong*. *pylong* must be
an instance of :c:type:`PyLongObject`.
Raise :exc:`OverflowError` if the value of *pylong* is out of range for a
:c:type:`size_t`.
Returns ``(size_t)-1`` on error.
Use :c:func:`PyErr_Occurred` to disambiguate.
.. c:function:: unsigned long long PyLong_AsUnsignedLongLong(PyObject *pylong)
.. index::
single: OverflowError (built-in exception)
Return a C :c:type:`unsigned long long` representation of *pylong*. *pylong*
must be an instance of :c:type:`PyLongObject`.
Raise :exc:`OverflowError` if the value of *pylong* is out of range for an
:c:type:`unsigned long long`.
Returns ``(unsigned long long)-1`` on error.
Use :c:func:`PyErr_Occurred` to disambiguate.
.. versionchanged:: 3.1
A negative *pylong* now raises :exc:`OverflowError`, not :exc:`TypeError`.
.. c:function:: unsigned long PyLong_AsUnsignedLongMask(PyObject *obj)
Return a C :c:type:`unsigned long` representation of *obj*. If *obj* is not
an instance of :c:type:`PyLongObject`, first call its :meth:`__index__`
method (if present) to convert it to a :c:type:`PyLongObject`.
If the value of *obj* is out of range for an :c:type:`unsigned long`,
return the reduction of that value modulo ``ULONG_MAX + 1``.
Returns ``(unsigned long)-1`` on error. Use :c:func:`PyErr_Occurred` to
disambiguate.
.. versionchanged:: 3.8
Use :meth:`__index__` if available.
.. versionchanged:: 3.10
This function will no longer use :meth:`__int__`.
.. c:function:: unsigned long long PyLong_AsUnsignedLongLongMask(PyObject *obj)
Return a C :c:type:`unsigned long long` representation of *obj*. If *obj*
is not an instance of :c:type:`PyLongObject`, first call its
:meth:`__index__` method (if present) to convert it to a
:c:type:`PyLongObject`.
If the value of *obj* is out of range for an :c:type:`unsigned long long`,
return the reduction of that value modulo ``ULLONG_MAX + 1``.
Returns ``(unsigned long long)-1`` on error. Use :c:func:`PyErr_Occurred`
to disambiguate.
.. versionchanged:: 3.8
Use :meth:`__index__` if available.
.. versionchanged:: 3.10
This function will no longer use :meth:`__int__`.
.. c:function:: double PyLong_AsDouble(PyObject *pylong)
Return a C :c:type:`double` representation of *pylong*. *pylong* must be
an instance of :c:type:`PyLongObject`.
Raise :exc:`OverflowError` if the value of *pylong* is out of range for a
:c:type:`double`.
Returns ``-1.0`` on error. Use :c:func:`PyErr_Occurred` to disambiguate.
.. c:function:: void* PyLong_AsVoidPtr(PyObject *pylong)
Convert a Python integer *pylong* to a C :c:type:`void` pointer.
If *pylong* cannot be converted, an :exc:`OverflowError` will be raised. This
is only assured to produce a usable :c:type:`void` pointer for values created
with :c:func:`PyLong_FromVoidPtr`.
Returns ``NULL`` on error. Use :c:func:`PyErr_Occurred` to disambiguate.