Using $_ as the primary method of passing parameters to a function does not seem like good style to me. A common pattern amongst Perl's built-ins though is to pass a parameter, but use $_ when no parameter is passed. A la:

sub f3 {
   my $input = @_ ? shift : $_;
   return $input + 1;
}
[download]

If you're using a vaguely recent version of Perl, the underscore prototype makes this simpler (and magically works with lexical $_):

sub f4 (_) {
   my $input = shift;
   return $input + 1;
}
[download]