Webmaster Forum / Perl / Getting Started / July 2008

(Code reformatted for legibility)

use strict;
use warnings;

my %guide;

get_list(undef, undef, {a => 1, b => 2, c => 3});

sub get_list {

 my ($black_list, $table, $crit) = @_;

 # $crit is a hash reference containing key to search and search
 # expression, for example start=Jul 07
 #
 my $listings;

 # This is a loop through hash containing key, value pairs of field,
 # value and placing into an array
 #
 my @crit;
 foreach my $keys (keys %{$crit}){
   push @crit,'{'."'".$keys."'".'}=~'.$crit->{$keys};
 }

 my $crit1 = join ' and ', @crit; ### array to string ###

 ### This is the record definition from  a master hash ###

 ###loop start ###

 foreach my $guides (sort {
     $guide{$a}->{'start'} <=> $guide{$b}->{'start'}
   } keys %guide) {

   push @{$listings}, [
     $guide{$guides}->{'id'},
     $guide{$guides}->{'Channel'},
     substr($guide{$guides}->{'start1'},0,16),
     $guide{$guides}->{'start'},
     substr($guide{$guides}->{'stop1'},0,16),
     $guide{$guides}->{'stop'},
     $guide{$guides}->{'name'},
     $guide{$guides}->{'cat0'}
   ];

   # here I want an if statement to run that is generated depending on what
   # keys are in the oringinal %crit hash. Number of arguments variable

   # if $crit1;

   # this is the problem rather than searching on the value of
   # $guide{$guides}-> it prints it out as a literal
 }
}

I'm not sure what you're trying to do here. The code is very unclear, so
I've run your code with a call of

 get_list(undef, undef, {a => 1, b => 2, c => 3});

and I've found that for this input you're building a string in $crit1 of

 {'c'}=~3 and {'a'}=~1 and {'b'}=~2

which isn't valid Perl (well it's syntactically correct, but you're applying
regular expressions to anonymous hashes with a single entry, which is nonsense.

Can you explain a little better what it is that you're trying to do please? Then
we may be able to help you. It looks like you're trying to write Perl code at
run time, for which you need eval(), but there are almost always better ways to
do things than to use eval.

Rob

Hello,

[ Whitespace adjusted for clarity. ]

So 'start' is the key and 'Jul 07' is the value?

Why the braces around $keys?  So you want to create the string (for
example) "{'start'}=~Jul 07"?  That doesn't make much sense.  Perhaps
you meant to use the %guide hash with the $keys key?

If my assumptions are correct then this may be what you want:

sub get_list {
    my ( $black_list, $table, $crit ) = @_;

    my %flags;
    for my $key ( keys %$crit ) {
        $flags{ $key } = $guide{ $key } =~ $crit->{ $keys };
        }

    my $listings;
    for my $guides ( sort { $guide{ $a }{ start } <=> $guide{ $b }{
start } } keys %guide ) {
        push @$listings, [
            @{ $guide{ $guides } }{ qw/id Channel/ },
            substr( $guide{ $guides }{ start1 }, 0, 16 ),
            $guide{ $guides }{ start },
            substr( $guide{ $guides }{ stop1 }, 0, 16 ),
            @{ $guide{ $guides } }{ qw/stop name cat0/ },
            ]
                if $flags{ $guides };
        }
    }

John