#!/usr/bin/perl
use strict;
use warnings;

my $sub = 'do_this';

{
    no strict "refs";
    print $sub->("Fred");
}


sub do_this {
   my $var = shift;
   return "My name is $var";
}

sub do_that {
   my $var = shift;
   return "My name is not $var";
}
__END__
My name is Fred