list index()

zzbbaadd at aol.com zzbbaadd at aol.com
Fri Aug 31 01:42:50 CEST 2007


On Aug 30, 4:31 pm, Ben Finney <bignose+hates-s... at benfinney.id.au>
wrote:
> zzbba... at aol.com writes:
> > In my case of have done os.listdir() on two directories. I want to see
> > what files are in directory A that are not in directory B.
>
> You get that information unambiguously. It's an exceptional case,
> since there's no index to return, so it throws an exception.
>
> > I have used exceptions in other languages and only do so on logic
> > that should never happen.
>
> You're confusing "assert" ("this should always be true") with
> "exception" ("this is an exception to the the normal flow of this
> process").
>
> An exception isn't "something that should never happen", it's
> something that is entirely possible and needs to be handled somehow.

I don't think that is the definition used across computer science.

It suddenly dawned on me that what would be best would be a contains()
(or IN syntax for those who can't afford to wait) for lists.

if mylist.contains("hello):

>
> --
>  \       "Always do right. This will gratify some people, and astonish |
>   `\                                         the rest."  -- Mark Twain |
> _o__)                                                                  |
> Ben Finney





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