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Re: Returning data from an eval

by tlm (Prior)
on Aug 02, 2005 at 13:51 UTC ( #480180=note: print w/replies, xml ) Need Help??


in reply to Returning data from an eval

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).

the lowliest monk

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