use strict;

sub decorate {
   my ($cb,$text) = @_;
   return $cb->($text);
}

my %sub = (
   bold => sub { return '<b>' . shift() . '</b>' },
   ital => sub { return '<i>' . shift() . '</i>' },
   undl => sub { return '<u>' . shift() . '</u>' },
);

for (keys %sub) {
   print decorate($sub{$_},'foobar'), "\n";
}