use strict;
use warnings;

use B::Deparse;
{
  package Before;
  use overload '&{}' => sub {
    my ( $f ) = @_;
    my $s=B::Deparse->new()->coderef2text($f);

    # note: this will *NOT* work if $f uses package variables
    # this will also not work if $f uses certain global variables
    #
    # namely, if $f uses global variables from
    # the namespace where it is defined. At least for 5.8.8
    # B::Deparse erases the namespace name: i.e. 
    #   { package Foo; our $X=100;  my $f=sub { print "$Foo::X\n" } }
    # will be deparsed as:  sub { print "${X}\n" }.
    # Since ${X} is undefined in package Before, 
    # Perl will complain about undefined variables.

    $f=eval 'sub {'.$s.'}';
    return sub {
      print "Stuff before\n";
      goto &$f;
    }
  }
}

my $cr=bless(sub {print "Hello @_\n" },'Before');
$cr->('tweedledum', 'tweedledee');
$cr->('walrus','carpenter');