# Old Buffer Protocol

3.0 版後已棄用.

These functions were part of the "old buffer protocol" API in Python 2. In Python 3, this protocol doesn't exist anymore but the functions are still exposed to ease porting 2.x code. They act as a compatibility wrapper around the new buffer protocol, 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 `PyObject_GetBuffer()` (or the `y*` or `w*` format codes with the `PyArg_ParseTuple()` family of functions) to get a buffer view over an object, and `PyBuffer_Release()` when the buffer view can be released.

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 `TypeError` on error.

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 `TypeError` on error.

int `PyObject_CheckReadBuffer`(PyObject *o)

  如果 o 支持单段可读缓冲接口则返回 `1`。 否则返回 `0`。 此函数总是会成功执行。

  请注意此函数会尝试获取并释放一个缓冲区，并且在调用对应函数期间发生的异常会被屏蔽。 要获取错误报告则应改用 `PyObject_GetBuffer()`。

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 `TypeError` on error.