#! /usr/bin/perl -w

use strict;

sub foo { "this is foo" }
sub bar { "this is bar" }

my @later;
sub do_it {
  my $ref = shift;
  if( ref($ref) eq 'CODE' ) {
    print "do it now: ", $ref->(), "\n";
  }
  elsif( ref($$ref) eq 'CODE' ) {
    push @later, $$ref;
  }
}

do_it( \&foo );
do_it( \\&bar );

print "deferred ", $_->(), "\n" for @later;