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.. highlightlang:: c
Old buffer API
--------------
.. deprecated:: 3.0
These functions were part of the "old buffer protocol" API in Python 2.
In Python 3, these functions are still exposed for ease of porting code.
They act as a compatibility wrapper around the :ref:`new buffer API
<bufferobjects>`, but they don't give you control over the lifetime of
the resources acquired when a buffer is exported.
Therefore, it is recommended that you call :cfunc:`PyObject_GetBuffer`
(or the ``y*`` or ``w*`` :ref:`format codes <arg-parsing>` with the
:cfunc:`PyArg_ParseTuple` family of functions) to get a buffer view over
an object, and :cfunc:`PyBuffer_Release` when the buffer view can be released.
Buffer Protocol
===============
.. cfunction:: int PyObject_AsCharBuffer(PyObject *obj, const char **buffer, Py_ssize_t *buffer_len)
Returns a pointer to a read-only memory location usable as character-based
input. The *obj* argument must support the single-segment character buffer
interface. On success, returns ``0``, sets *buffer* to the memory location
and *buffer_len* to the buffer length. Returns ``-1`` and sets a
:exc:`TypeError` on error.
.. cfunction:: int PyObject_AsReadBuffer(PyObject *obj, const void **buffer, Py_ssize_t *buffer_len)
Returns a pointer to a read-only memory location containing arbitrary data.
The *obj* argument must support the single-segment readable buffer
interface. On success, returns ``0``, sets *buffer* to the memory location
and *buffer_len* to the buffer length. Returns ``-1`` and sets a
:exc:`TypeError` on error.
.. cfunction:: int PyObject_CheckReadBuffer(PyObject *o)
Returns ``1`` if *o* supports the single-segment readable buffer interface.
Otherwise returns ``0``.
.. cfunction:: int PyObject_AsWriteBuffer(PyObject *obj, void **buffer, Py_ssize_t *buffer_len)
Returns a pointer to a writable memory location. The *obj* argument must
support the single-segment, character buffer interface. On success,
returns ``0``, sets *buffer* to the memory location and *buffer_len* to the
buffer length. Returns ``-1`` and sets a :exc:`TypeError` on error.
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