* Steven D'Aprano wrote:
> You don't need a comment warning that you are catching SystemExit
> because parse_args raises SystemExit, any more than you need a comment
> saying that you are catching ValueError because some function raises
> ValueError. The fact that you are catching an exception implies that
> the function might raise that exception. A comment like:
>
> "Catching SystemExit because parse_args() throws SystemExit on parser
> errors."
>
> is up them with comments like this:
>
> x += 1 # Add 1 to x.
It's semantically different. You usually don't catch SystemExit directly,
because you want your programs to be stopped. Additionally, a library
exiting your program is badly designed, as it's unexpected. Thatswhy such a
comment is useful.
Here's what I'd do: I'd subclass SystemExit in this case and raise the
subclass from argparse. That way all parties here should be satisifed. (I
do the same all the time in my signal handlers - that's another reason I'd
rather not catch SystemExit directly as well :-)
nd
--
"Umfassendes Werk (auch fuer Umsteiger vom Apache 1.3)"
-- aus einer Rezension
<http://pub.perlig.de/books.html#apache2>
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