[Python-Dev] Extending struct.unpack to produce nested tuples

Guido van Rossum guido at python.org
Sat Nov 22 18:41:03 EST 2003

> I was wondering if there would be any interest in extending the
> struct.unpack format notation to be able to express groups of data
> with parenthesis.
> For example:
> >>> data = struct.pack('iiii', 1, 2, 3, 4)
> >>> struct.unpack('i(ii)i', data)  # Note the parentheses
> (1, (2, 3), 4)
> Use Case:  I have a program written in C that contains a bunch of
> aggregate data structures (arrays of structs, structs containing
> arrays, etc.) and I'm transmitting these structures over a socket
> connection to a Python program that then unpacks the data using the
> struct module.  Problem is that I have to unpack the incoming data as
> a flat sequence of data elements, and then repartition the sequence
> into nested sequences to better reflect how the data is structured in
> the C program.  It would be more convenient to express these groupings
> as I'm unpacking the raw data.
> I'm sure there are plenty of other use cases for such a feature.

This is a reasonable suggestion.  You should also be able to write
things like '4(ii)' which would be equivalent to '(ii)(ii)(ii)(ii)'.
Please use SourceForge to upload a patch.  Without a patch nobody is
going to be interested though, I suspect, so don't wait for someone
else to implement this.

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

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