[Python-3000] PEP Draft: Enhancing the buffer protcol

[Jim Jewett]

On 2/27/07, Travis E. Oliphant <oliphant.travis at ieee.org> wrote:

> Rationale

(This was a good section; thank you.)


>     5. There is no shape information provided for the memory.  But,
>        several array-like Python types could make use of a standard
>        way to describe the shape-interpretation of the memory
>        (!wxPython, GTK, pyQT, CVXOPT, !PyVox, Audio and Video
>        Libraries, ctypes, !NumPy, data-base interfaces, etc.)

Are the "!" characters meaningful?

>       This view object should be used in the other API calls and
>       does not need to be decref'd.  It should be "released" if the
>       interface exporter provides the bf_releasebuffer function.

Pity you can't use decref instead of release ... could the description
object be treated as a real object, and decrefed to indicate release?
(Or are there lots of tiny buffers with identical large descriptions?)

> Additions to the struct string-syntax
>
>    The struct string-syntax is missing some characters to fully
>    implement data-format descriptions already available elsewhere (in
>    ctypes and NumPy for example).  Here are the proposed additions:
>
>    Character         Description
>    ==================================
>    '1'               bit (number before states how many bits)

How do you distinguish the "1" for bit from a trailing 1 in a number?
It sounds like

   "21" means 2 bits
   "2g" means 2 long doubles
   "21g" means either 2 bits and a long double, or 21 long doubles.

>    Code should also be able to request contiguous memory if needed and
>    objects exporting the buffer interface should be able to handle
>    that either by raising an error

Do you want to specify the error?

-jJ