On Tue, Aug 12, 2003 at 12:15:59AM +0000, Backward Thinker wrote:
>
> I don't have a python interpreter handy, so take this with a grain of salt.
>
> > In C and the like, you can simply execute a return or exit anywhere
> > in main(), but not in python.
>
> Return should work from anywhere in a function definition. If you're not
> in a function, then you are probably looking for sys.exit().
>
> import sys
> sys.exit(42)
> or more likely,
> sys.exit()
That would be the correct answer. I searched the internet a little after
I wrote this email, and found the sys.exit() function in some sample
code on the internet.
> (0 is probably the default)
>
> > The second problem is sometimes related to the first. Apparently,
> > when you open a file, as in:
> >
> > open(filename, 'r')
> >
> > if the file doesn't exist, you get this hairy error message and the
> > interpreter just dumps out. I've never seen this kind of behavior
> > before. I'd expect something more like
> >
> > if open(filename, 'r'):
> > do_stuff
> > else:
> > couldnt_open_the_file_stuff
> >
> > But that doesn't work. The only way I can see around this is to
> > surround every call to open() with a try/except block. That's clunky
> > to me.
> > Anyone know something I don't?
>
> Yup, that's kinda how python is. Errors typically generate exceptions, and
> python catches the exception. Depending on how many opens you have and how
> much you hate try except blocks, you can write your own open function once
> with one try except block, which returns None if it catches an exception.
> So instead of writing 50 try except blocks, you can just write the one
> function, and call your new function with the filename as an arg, and test
> if your function call returned a file object or None... no more try except
> blocks necessary.
<snip>
The exception thing explains why python acts so oddly (to me). The
single open_file() function is probably the best idea in the long run.
It's funny, I'm converting some perl code over to python. I normally
code in C, and for some reason, perl was vastly easier to learn than
python is. Weird.
Anyway thanks,
Paul
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