package bangbangbang;

use Filter::Simple;

FILTER_ONLY
  code => sub {
    s{ \s \Q!!!\E \s }
     { die("Deferred implementation can't be executed"); }gx
  };

q[ ichi ni san ];

##</code><code>##

use bangbangbang;

sub foo { !!! }
my $bar = sub { !!! };
sub baz { return !!! }

eval { foo()   } or warn "foo() - $@";
eval { &$bar() } or warn "bar() - $@";
eval { baz()   } or warn "baz() - $@";

__output__

foo() - Deferred implementation can't be executed at bbb_test.pl line 3.
bar() - Deferred implementation can't be executed at bbb_test.pl line 4.
baz() - Deferred implementation can't be executed at bbb_test.pl line 5.