in reply to Re: Re: Better way to search?
in thread Better way to search?

It's a hash slice.

It fills the hash %exts with the contents of your @exts array. The keys are set to the values in @exts, and the values in the hash are set to undef. That's why you need to test for exists rather than "truth"; because the values aren't "true", but the keys do exist.

Replies are listed 'Best First'.
Re: Re: Re: Re: Better way to search?
by r.joseph (Hermit) on Jan 05, 2001 at 06:23 UTC
    Ah, I see. So if I have this: 
    @exts = {'jpg','jpeg','gif');

%exts;
@exts{@exts} = ();

    [download]
    then we get an %exts array that is the same as this: 
    %exts = ('jpg'=>'','jpeg'=>'','gif'=>'');

    [download]
    Right? Why do you so @exts{@exts} and not %exts{@exts}?
[reply]
[d/l]
[select]
      Right? Why do you so @exts{@exts} and not %exts{@exts}?
      Because one's legal and the other isn't!

      A slice acts as an array. So therefore, the starting symbol is "at", meaning "array".

      -- Randal L. Schwartz, Perl hacker

[reply]
        Slices don't act like arrays in scalar context though.

        That has always bugged me. Personally I wish that Perl were a little less DWIM about: 

        $elem = @array[0];

        [download]
        If that did something completely unexpected to the novice, then they might learn sooner what the correct notation is...
[reply]
[d/l]
        Sorry to keep bugging y'all, but this is really helpful and interesting. So if I did something like this: 
        @exts{@exts} = @exts;

        [download]
        would that make both the keys AND the values equal (and obviously, the values of the @exts array)?
[reply]
[d/l]
      Regarding the first question: not quite, s/''/undef/g, and then they're the same.
[reply]

In Section Seekers of Perl Wisdom