[Python-Dev] pre-PEP: The Safe Buffer Interface

[Guido van Rossum]

Thomas,

I like your PEP.  Could you clean it up (changing 'large' into 'safe'
etc.) and send it to Barry?  Some comments:

> Backward Compatibility
> 
>     There are no backward compatibility problems.

That's a simplification of the truth -- you're adding two new fields
to an existing struct.  But the flag bit you add makes that old and
new versions of the struct can be distinguished.

>     It may be a good idea to expose the following convenience functions:
> 
>         int PyObject_AsSafeReadBuffer(PyObject *obj,
>                                       void **buffer,
>                                       size_t *buffer_len);
> 
>         int PyObject_AsSafeWriteBuffer(PyObject *obj,
>                                        void **buffer,
>                                        size_t *buffer_len);
> 
>     These functions return 0 on success, set buffer to the memory
>     location and buffer_len to the length of the memory block in
>     bytes. On failure, they return -1 and set an exception.

Please make these a manadatory part of the proposal.

Please also try to summarize the discussion so far here.  My personal
opinion: locking seems the wrong approach, given the danger of
deadlock; Scintilla can use the existing buffer protocol, assuming its
buffer doesn't move as long as you don't release the GIL and don't
make calls into Scintilla.

--Guido van Rossum (home page: http://www.python.org/~guido/)