sub wrap_sub {
  my ($class, $function) = @_;

  no strict 'refs';
  no warnings 'redefine';

  my $referent = \&{"$class\::$function"};

  my $wrap_sub = sub {
    warn 'before';
    $referent->( @_ );
    warn 'after';
  };

  warn "wrap_sub wrapping: $class\::$function";
  no warnings 'redefine';
  *{"$class\::$function"} = $wrap_sub;
  return;
}

##</code><code>##

sub foo {
  warn 'fooooo';
}
__PACKAGE_->wrap_sub("foo");