Cecil Westerhof wrote:
> I have a function to fetch a message from a file:
> def get_indexed_message(message_filename, index):
> """
> Get index message from a file, where 0 gets the first message
> """
>
> return open(expanduser(message_filename),
> 'r').readlines()[index].rstrip()
>
> What is more the Python way: let the exception fire like this code
> when index is to big, or catching it and returning None?
Fire an exception, but you may also allow the user to provide a default.
> I suppose working zero based is OK.
Not just OK, it's de rigueur.
You didn't ask for that, but
(1)
with open(...) as f:
return f.readlines()[index].rstrip()
is preferrable because it closes the file in a controlled way and
(2) you may want to take measures to limit memory usage, e. g.
assert index >= 0
try:
[line] = itertools.islice(f, index, index+1)
except ValueError:
raise IndexError
return line.rstrip()
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