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Re^2: Little annoying mistakes ... of others

by jeffa (Chancellor)
on Dec 07, 2008 at 16:06 UTC ( #728735=note: print w/ replies, xml ) Need Help??


in reply to Re: Little annoying mistakes ... of others
in thread Little annoying mistakes ... of others

Actually ... i would desire this:

use strict; use warnings; my $arg = shift || 'boo'; my @valid = qw( goo moo foo voo doo poo ); print "$arg matches\n" if grep /$arg/, @valid;

But this bring up an annoyance as well, because this mistake will compile and always return true (as long as the array being checked is not empty):

# wrong way ahead! print "$arg matches\n" if grep $arg, @valid;
Oops!

jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)


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Re^3: Little annoying mistakes ... of others
by szabgab (Priest) on Dec 28, 2008 at 19:26 UTC
    Wow, I am writing down the examples as test cases but I can't figure out why is the second example always true?

    could you please explain?

      I think this:

      print "$arg matches\n" if grep $arg, @valid;

      Is equivalent to this:

      print "$arg matches\n" if grep { $arg } @valid;
      So as long as @valid and $arg are not false, then the match will also be true. (If $arg is 0 (zero) then the second example will not always be true.)

      jeffa

      L-LL-L--L-LL-L--L-LL-L--
      -R--R-RR-R--R-RR-R--R-RR
      B--B--B--B--B--B--B--B--
      H---H---H---H---H---H---
      (the triplet paradiddle with high-hat)
      

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