#!/usr/bin/perl -w
use strict;

my $A = q(my $arg = shift;print "A ";print "$arg\n";);
my $B = q(print "B\n";);
my %subs = (
            A => sub { $A },
            B => sub { $B },
            O => sub {my $arg = shift;print "O ";print "$arg\n";}
        );

for my $key (keys %subs ) {
    eval &{$subs{$key}}(10) ;
}