use strict;
use warnings;

my $data         = "Just another Perl hacker,";
my $action       = 'subst';
my $pattern      = 'hacker';
my $substitution = 'enthusiast';

my %actions = (
  match    => 
    sub { my $rv = $_[0] = ~m/$_[1]/;       return( $rv, [@-], [@+] ) },
  subst    => 
    sub { my $rv = $_[0] =~ s/$_[1]/$_[2]/; return( $rv, [@_], [@+] ) },
);

exists $actions{$action} or die "Invalid action: $action";
my @results = $actions{$action}->($data, $pattern, $substitution);
print $data, "\n";