problems when unpacking tuple ...

[harold]

Dear all,

Maybe I stared on the monitor for too long, because I cannot find the
bug ...
My script "transition_filter.py" starts with the following lines:

import sys

for line in sys.stdin :
    try :
        for a,b,c,d in line.split() :
            pass

    except ValueError , err :
        print line.split()
        raise err

The output (when given the data I want to parse) is:
['0.0','1','0.04','0']
Traceback (most recent call last):
  File "transition_filter.py", line 10, in ?
    raise err
ValueError: need more than 3 values to unpack

What is going wrong here? Why does python think that
I want to unpack the outcome of line.split() into three
values instead of four? I must be really tired, but I just
cannot see the problem. Any clues??

Thanks,

- harold -