using struct module on a file
Hia! I need to read a file containing packed binary data. For that, I find the struct module pretty convenient. What I always need to do is reading a chunk of data from the file (either using calcsize() or a struct.Struct instance) and then parsing it with unpack(). For that, I repeatedly write utility functions that help me do just that, but I can't imagine that there is no better way for that. Questions: 0. Am I approaching this from the wrong direction? I'm not a programming noob, but rather new to Python still. 1. The struct module has pack_into() or unpack_from(), could I somehow combine that with a file? 2. Is there some easier way to read files? I know about array and xdrlib, but neither really fit my desires. 3. Failing all that, would you consider this a useful addition to the struct module, i.e. should I write a feature request? Thanks! Uli -- http://mail.python.org/mailman/listinfo/python-list
Re: using struct module on a file
On Nov 18, 4:42 pm, Ulrich Eckhardt dooms...@knuut.de wrote:
Hia!
I need to read a file containing packed binary data. For that, I find the
struct module pretty convenient. What I always need to do is reading a chunk
of data from the file (either using calcsize() or a struct.Struct instance)
and then parsing it with unpack(). For that, I repeatedly write utility
functions that help me do just that, but I can't imagine that there is no
better way for that.
Questions:
0. Am I approaching this from the wrong direction? I'm not a programming
noob, but rather new to Python still.
1. The struct module has pack_into() or unpack_from(), could I somehow
combine that with a file?
2. Is there some easier way to read files? I know about array and xdrlib,
but neither really fit my desires.
3. Failing all that, would you consider this a useful addition to the struct
module, i.e. should I write a feature request?
Thanks!
Uli
First time I've seen zero based indexing for paragraph markers :)
unpack_from() will work on anything that supports the buffer
interface.
To work with files you can use something like:
my4chars = struct.Struct('4c')
def struct_read(s, f):
return s.unpack_from(f.read(s.size))
Which isn't hideously painful.
Jon.
--
http://mail.python.org/mailman/listinfo/python-list
Re: using struct module on a file
On Wed, Nov 18, 2009 at 11:42 AM, Ulrich Eckhardt dooms...@knuut.de wrote: Hia! I need to read a file containing packed binary data. For that, I find the struct module pretty convenient. What I always need to do is reading a chunk of data from the file (either using calcsize() or a struct.Struct instance) and then parsing it with unpack(). For that, I repeatedly write utility functions that help me do just that, but I can't imagine that there is no better way for that. Questions: 0. Am I approaching this from the wrong direction? I'm not a programming noob, but rather new to Python still. 1. The struct module has pack_into() or unpack_from(), could I somehow combine that with a file? 2. Is there some easier way to read files? I know about array and xdrlib, but neither really fit my desires. 3. Failing all that, would you consider this a useful addition to the struct module, i.e. should I write a feature request? Thanks! Uli You might look at Construct: http://construct.wikispaces.com/ ~Simon -- http://mail.python.org/mailman/listinfo/python-list
