http://www.perlmonks.org?node_id=1021896


in reply to Name "main::a" used only once: possible typo

This is a common problem with no known great solution (if there is a great solution I hope someone will show it so that we can submit patches). It also annoys anyone using List::MoreUtils pairwise, for about the same reason. Several ideas were tossed around in the List::MoreUtils RT as to how to fix the problem, but none were ideal, and none fixed it in 100% of use cases (including my attempt).

The easiest solution is still annoying, and looks like this:

reduce { no warnings 'once'; $a * $b } 1 .. 6;

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Update: I see that the List::Util RT suggests something like this: 

reduce { our ( $a, $b ); $a * $b } 1 .. 6;

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Dave

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Re^2: Name "main::a" used only once: possible typo
by ikegami (Patriarch) on Mar 06, 2013 at 04:48 UTC
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[d/l]
      I'd probably put the our ($a,$b) outside of that block, but this is what I had in mind. I was just interested in more options. - Thanks 
      out ($a, $b);
reduce { $a * $b } 1 .. 6;

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[reply]
[d/l]
        I was just interested in more options.

        This is kind of old-school and amounts to the same thing as sticking an  our ($a, $b); statement somewhere, but it's another option: 

        >perl -wMstrict -le
"use List::Util qw/reduce/;
 use vars qw($a $b);
 ;;
 print reduce { $a * $b } 1..6;
"
720

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[d/l]
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