i was trying to get a combination of map and grep working to set a selected element to pass to HTML::Template without using a foreach loop.

Um, why? What's wrong with foreach loops?

In my opinion, code like this:

my $parts = [ 'Part1', 'Part2','Part3' ];

my $newLoop = [ grep { $_->{SELECTED}++ 
                  if $_->{PARTNAME} eq $row->{title}, $_ }
                map +{ 'PARTNAME' => $_ }, @$parts ] ;

[download]

is bad even if it works, which--as you found out--it doesn't. grep/map are great as list filters, when you want to build one list from another, but they force you to stuff all of your code in one tiny block/expression. foreach is the general-purpose list iterator, and you should always be ready to fallback on it if grep or map get too hairy, like revdiablo showed you:

for (@$parts) {
  my $hash = { PARTNAME => $_ };

  $hash->{SELECTED}++
      if $_ eq $row->{title};

  push @$newLoop, $hash;
}

[download]

foreach is your friend.

UPDATE: -2? What was so objectionable about suggesting Perl programmers use a clearer construct over a shorter one?

In reply to Re: "advanced" Perl functions and maintainability by William G. Davis
in thread "advanced" Perl functions and maintainability by geektron

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