Strange loop behavior

[Arnaud Delobelle]

On Mar 26, 8:51 am, Gabriel Rossetti
<gabriel.rosse... at mydeskfriend.com> wrote:
> Gabriel Rossetti wrote:
> > Hello,
>
> > I wrote a program that reads data from a file and puts it in a string,
> > the problem is that it loops infinitely and that's not wanted, here is
> > the code :
>
> >     d = repr(f.read(DEFAULT_BUFFER_SIZE))
> >     while d != "":
> >         file_str.write(d)
> >         d = repr(f.read(DEFAULT_BUFFER_SIZE))
>
> > I also tried writing the while's condition like so : len(d) > 0, but
> > that doesn't change anything. I tried step-by-step debugging using
> > PyDev(eclipse plugin) and I noticed this, once the while was read once,
> > it is never re-read, basically, the looping does happen, but just in
> > between the two lines in the loop's body/block, it never goes on the
> > while and thus never verifies the condition and thus loops forever. I
> > had been using psyco (a sort of JIT for python) and so I uninstalled it
> > and restarted eclipse and I still get the same thing. This looks like
> > some bug, but I may be wrong, does anybody understand what's going on here?
>
> > Thanks,
> > Gabriel
>
> > PS
> > And yes I checked, the "d" variable is en empty string at some point, so
> > the looping should stop.
>
> Ok, I get it, the repr() function actually returns a string with quote
> characters around it, thus the length is never 0, but 2. The reason I
> began using the repr() function is that the str() and unicode()
> constructors didn't accept the data read, because it was bigger than
> ord(128) (or something like that. I'm trying to read a binary file and
> put it's contents in an xml message to send via the network, so that I
> can re-create it on the other side. I do need to keep the xml aspect
> though. Is there a better way of doing this?
>
> Thanks,
> Gabriel

Have a look at the uu and base64 modules:

http://docs.python.org/lib/module-uu.html
http://docs.python.org/lib/module-base64.html

--
Arnaud