http://www.perlmonks.org?node_id=992452


in reply to Re^2: var comparison
in thread var comparison

If your list of possible values gets long, you could store them as keys of a hash and then check for existence or definedness in the hash.

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Re^4: var comparison
by nemesisgus (Acolyte) on Sep 08, 2012 at 18:32 UTC

    Yes, that's one of the solutions MidLifeXis proposed and I think it's also considered a Perl "best practice".

[reply]
      hmm, nobody gave you a code example ?

        DB<100> @option{qw/a b c/}=()
 => (undef, undef, undef)
 
  DB<101> exists $option{a}
 => 1                         #true
 
  DB<102> exists $option{d}
 => ""                        #false

      [download]

      but smart-match should be safe as long as you don't forget the quotes.

      Cheers Rolf

[reply]
[d/l]

        Nice hash slice, thanks!

        Just let me polish up your code so other newbies don't get confused:

        my %option;
@option{qw/a b c/}=();

# my %option = (
#  'a' => undef,
#  'b' => undef,
#  'c' => undef
# );

exists $option{a} and print 'true';

exists $option{d} or print 'false';

        [download]

        PS: what the h**l is DB <...> ?

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