Marc-Andre Lemburg <m...@egenix.com> added the comment: STINNER Victor wrote: > > STINNER Victor <victor.stin...@haypocalc.com> added the comment: > >> Note that the buffer interface release API is meant to protect >> against such modifications, so I don't see why rejecting objects >> that do implement this API should be rejected. > > As I explained, the release API is *not* used by PyObject_AsCharBuffer() in > Python 2.7 and 3.2. > > Pseudo-code example: > --- > PyObject_AsCharBuffer(obj, &str, &size) > ... modify or destroy obj ... > str is no more valid here > ---
Right, but as I explained before: this doesn't really happen in practice, otherwise we would have had issues with these APIs long before the Py_buffers were introduced. Note that the same comment applies to PyObject_AsReadBuffer() and PyObject_AsWriteBuffer(). For Python 2.7 you can't change anything anymore. For Python 3.2 you could start a deprecation process as outlined in PEP 4, if you feel this really is such a big issue. >> Restricting the API to read-only buffers would seriously limit >> it's functionality. I'm -1 on doing that. > > PyObject_AsCharBuffer() is dangerous because the caller has to ensure that > the object is not modified or destroyed. Antoine proposes to deprecated > PyObject_AsCharBuffer(). > > PyObject_GetBuffer() can replace PyObject_AsCharBuffer(): it's easy to get > the pointer to the buffer content (view.buf) and the size (view.len) using > PyObject_GetBuffer(), and it does protect the buffer against modification or > destuction thanks to the release API (PyBuffer_Release). But > PyObject_GetBuffer() is maybe a little bit to low level, eg. it doesn't check > that the buffer is contiguous, and it requires a flag argument. A new > function is maybe needed to replace PyObject_AsCharBuffer(). Eg. > PyObject_GetCharBuffer() which will call PyObject_GetBuffer() (the caller > will then have to call PyBuffer_Release() to release the buffer). > > Example: > --- > PyObject_GetCharBuffer(obj, &view, &str, &size) > ... use str and size ... > PyBuffer_Release(view); > --- > or just > --- > PyObject_GetCharBuffer(obj, &view) > ... use view.buf and view.len ... > PyBuffer_Release(view); > --- Why add a new function ? Python 3.2 doesn't provide a way to access a *character* buffer version of an object anymore. Not that this is good, or shouldn't be readded at some point, but right now, we don't have a need for such an API. ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue9602> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
