For this purpose, I've always just stored the ad-hoc value relationships as key/value pairs in a hash, and then returned the value for the key:

#!/usr/bin/perl
use strict;

my  $TRUE           = 1;
my  $FALSE          = 0;

my  $KEY_ADHQRY     = 'ADHQRY';         # Hash key for the ad hoc Quer
+y
my  $KEY_ADHVAL     = 'ADHVAL';         # Hash key for the ad hoc Valu
+e

my   %Adhinf = ();                      # Ad hoc information

# Get the ad hoc query/response values and populate the hash
{
    print "Enter ad hoc values list in the following format:  query->v
+alue|query->value|query->value\n";
    my $reqahv = <STDIN>;
    chomp $reqahv;
    my @adhelt = split /\|/, $reqahv;
    foreach my $adhelt (@adhelt)
    {
        my $wrkelt = $adhelt;
        $wrkelt =~ s/^\s+//;
        $wrkelt =~ s/\s+$//;
        my ($adhqry, $adhval) = split /\s*\-\>\s*/, $wrkelt, 2;
        my $adhkey = uc $adhqry;
        $Adhinf{$adhkey}{$KEY_ADHQRY} = $adhqry;
        $Adhinf{$adhkey}{$KEY_ADHVAL} = $adhval;
    }
}

# Test the query/response behavior
{
    my $prcflg = $TRUE;
    while ($prcflg)
    {
        print "    Enter query: ";
        my $reqqry = <STDIN>;
        chomp $reqqry;
        if ($reqqry =~ /^\s*$/)
        {
            $prcflg = $FALSE;
            last;
        }
        else
        {
            my $reqrsp = getAdHocResponse($reqqry);
            print "       Response: $reqrsp\n";
            print "\n";
        }
    }
}

exit;

sub getAdHocResponse
{
    my ($reqqry, @arglst) = @_;
    if (!defined $reqqry) { $reqqry = ''; }

    my $retval = '{No Response}';

    my $reqkey = uc $reqqry;
    if (defined $Adhinf{$reqkey})
    {
        $retval = $Adhinf{$reqkey}{$KEY_ADHVAL};
    }

    return $retval;
}
[download]

And the test results:

C:\Steve\Dev\PerlMonks\P-2015-03-30@1459-Ad-Hoc-Conditionals>adhoc1.pl
Enter ad hoc values list in the following format:  query->value|query-
+>value|query->value
Steve->Pinger|Tom->Tony|Ronald->Kevin
    Enter query: mike
       Resposne: {No Response}

    Enter query: george
       Resposne: {No Response}

    Enter query: steve
       Resposne: Pinger

    Enter query: om
       Resposne: {No Response}

    Enter query: tom
       Resposne: Tony

    Enter query: kevin
       Resposne: {No Response}

    Enter query: ronald
       Resposne: Kevin

    Enter query:
[download]