$verbose=0;

sub not_say {
    print 'not saying';
}
sub say {
   print @_,"\n";
}

{
  no warnings;
  *say = \&not_say if not $verbose;
}

say 'test';

##</code><code>##

use strict;
use warnings;
no feature "say";

sub say {
   print "nothing";
}

say 'test';