Strange loop behavior

Gabriel Rossetti gabriel.rossetti at mydeskfriend.com
Wed Mar 26 09:35:07 CET 2008


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.

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