Re: Returning data from an eval

[tlm]

I'm surprised your second version does not work for you; it works for me.

use strict;
use warnings;

my @rules =
  ( q( return( "A", "Cat A" ) if $abs_diff < 75_000 and $source eq "IC
+E" ),
    q( return( "B", "Dog B" ) if $abs_diff < 75_000 and $source eq "FO
+O" ),
    q( return( "C", "Pig C" ) if $abs_diff < 75_000 and $source eq "BA
+R" ), );

my $abs_diff = 0;
my $source = 'FOO';

my @results = eval_rules();

print "@results\n";

sub eval_rules {
  for my $rule ( @rules ) {
    my ( $cat, $comment ) = eval $rule;
    return ( $cat, $comment ) if $cat and $comment;
  }
}

__END__
% perl rules.pl 
B Dog B

If I were you, I'd code the rules without return, and so that the last expression in them is a clear, unambiguous value; e.g.

q( $abs_diff < 75_000 and $source eq "ICE" ? ( "A", "Cat A" ) : () )

Then you can write:

  for my $rule ( @rules ) {
    my @ret = eval $rule;
    return @ret if @ret;
  }

The way you have it, if the test is true, the eval will return a list, otherwise it returns undef, so simply testing for @ret wouldn't work (it will always have a non-zero length).