#!/usr/bin/perl -w

package Foo;
use constant CONSTANT => 2;

package main;
use Benchmark qw(cmpthese);
use strict;

my $object = bless \(my $dummy), 'Foo';

# Note: I use assignments to avoid the constant in void context 
# to be optimised away (that would be too fast for Benchmark
# to handle (try removing "my $foo =" for fun ;)).
cmpthese(-1, {
    object_method => sub { my $foo = $object->CONSTANT },
    class_method  => sub { my $foo = Foo->CONSTANT },
    direct_sub    => sub { my $foo = Foo::CONSTANT }
});
__END__
Benchmark: running class_method, direct_sub, object_method, each for at least 1 CPU seconds...
class_method:  2 wallclock secs ( 1.07 usr +  0.00 sys =  1.07 CPU) @ 401942.99/s (n=430079)
direct_sub:  2 wallclock secs ( 1.16 usr +  0.00 sys =  1.16 CPU) @ 3389792.24/s (n=3932159)
object_method:  1 wallclock secs ( 1.14 usr +  0.00 sys =  1.14 CPU) @ 548745.61/s (n=625570)
                   Rate  class_method object_method    direct_sub
class_method   401943/s            --          -27%          -88%
object_method  548746/s           37%            --          -84%
direct_sub    3389792/s          743%          518%            --