[Python-Dev] An updated extended buffer PEP (original) (raw)

Greg Ewing greg.ewing at canterbury.ac.nz
Tue Mar 27 08:43:42 CEST 2007

Here's another idea, to allow multiple views of the same buffer with different shape/stride info to coexist, but without extra provider objects or refcount weirdness. Also it avoids using calls with a brazillion arguments.

struct bufferinfo { void **buf; Py_ssize_t *len; int *writeable; char **format; int *ndims; Py_ssize_t **shape; Py_ssize_t **strides; int **isptr; };

int (*getbuffer)(PyObject *obj, struct bufferinfo *info);

int (*releasebuffer)(PyObject *obj, struct bufferinfo *info);

If the object has constant shape/stride info, it just fills in the info struct with pointers to its own memory, and does nothing when releasebuffer is called (other than unlocking its buffer).

If its shape/stride info can change, it mallocs memory for them and copies them into the info struct. When releasebuffer is called, it frees this memory.

It is the responsibility of the consumer to ensure that the base object remains alive until releasebuffer has been called on the info struct (to avoid leaking any memory that has been malloced for shapes/strides).

-- Greg

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