[Python-Dev] Buffer protocol for io.BytesIO?

[Antoine Pitrou]

On Fri, 3 Sep 2010 20:44:01 +1000
Nick Coghlan <ncoghlan at gmail.com> wrote:
> 
> It actually strikes me as a fairly bad thing, so I think you're right
> to distrust it. Better to follow the precedent set with getvalue() and
> require an explicit call to getbuffer(). The fact there are two
> options (immutable copy via getvalue() or mutable accessor via
> getbuffer()) is all the more reason not to make either conversion
> implicit.

Thank you for the advice. I think getbuffer() it will be :)

> > It could not be resized, but it could be modified (same as what happens
> > with bytearrays today). Actually, the buffer itself would be writable,
> > and allow modifying the BytesIO contents.
> 
> You may need to be careful with reads and writes while the buffer is
> exposed (e.g. throwing an exception until the buffer is released
> again). Perhaps the buffer accessor should be a context manager so it
> is easy to enforce prompt release?

That's an interesting idea. I was planning to return a memoryview
object (in order to hide the intermediate object, and make it really
minimal), so perhaps the context protocol should be enabled on
memoryviews?

(__enter__ would be a no-op, and __exit__ would release the internal
buffer and render it invalid, a bit like closing a file)

Regards

Antoine.