use strict;
use warnings;
use experimental "signatures";
use Carp;

{
    package BLA;

    sub new ($class,@properties) {
        return bless {@properties}, $class;
    }


    sub foo ($self, @val) {
        unless (@val){                  # getter
            return $self->{foo}
        } elsif (@val == 1) {           # setter
            return $self->{foo} = $val[0];
        } else {                        # ERROR
            local $" = ",";
            Carp::croak "Too many arguments for method 'BLA->foo(@val)'";
        }
    }
}




my $x = BLA->new(foo=>42);

warn "getter:", $x->foo;
warn "setter:", $x->foo(666);
warn "getter:", $x->foo;
warn "error:",  $x->foo(42,666);

##</code><code>##

-*- mode: compilation; default-directory: "d:/tmp/pm/" -*-
Compilation started at Fri Jan  8 21:39:32

C:/Perl_524/bin\perl.exe -w d:/tmp/pm/missing_param.pl 
getter:42 at d:/tmp/pm/missing_param.pl line 31.
setter:666 at d:/tmp/pm/missing_param.pl line 32.
getter:666 at d:/tmp/pm/missing_param.pl line 33.
Too many arguments for method 'BLA->foo(42,666)' at d:/tmp/pm/missing_param.pl line 34.

Compilation exited abnormally with code 255 at Fri Jan  8 21:39:33