[Python-Dev] an idea for improving struct.unpack api

[Gustavo J. A. M. Carneiro]

On Thu, 2005-01-06 at 13:17 +0000, Michael Hudson wrote:
> Ilya Sandler <ilya at bluefir.net> writes:
> 
> > A problem:
> >
> > The current struct.unpack api works well for unpacking C-structures where
> > everything is usually unpacked at once, but it
> > becomes  inconvenient when unpacking binary files where things
> > often have to be unpacked field by field. Then one has to keep track
> > of offsets, slice the strings,call struct.calcsize(), etc...
> 
> IMO (and E), struct.unpack is the primitive atop which something more
> sensible is built.  I've certainly tried to build that more sensible
> thing at least once, but haven't ever got the point of believing what
> I had would be applicable to the general case... maybe it's time to
> write such a thing for the standard library.

  I've been using this simple wrapper:

def stream_unpack(stream, format):
	return struct.unpack(format, stream.read(struct.calcsize(format)))

  It works with file-like objects, such as file, StringIO,
socket.makefile(), etc.  Working with streams is useful because
sometimes you don't know how much you need to read to decode a message
in advance.

  Regards.

> 
> Cheers,
> mwh
> 
-- 
Gustavo J. A. M. Carneiro
<gjc at inescporto.pt> <gustavo at users.sourceforge.net>
The universe is always one step beyond logic.
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