#!/usr/bin/perl
use strict;
use warnings;

package SillyClass2;

sub new {
	my $class = shift;
	bless \@_, $class;
}

sub modifySubset: lvalue {
	my( $self, $start, $end ) = @_;
	
	@{ $self }[ $start .. $end ]
	
	## Validate that all values in the slice being assigned are
	## non-zero, even and uniq

	# my %uniq;
	# die 'Bad value' 
	#	unless $end - $start == grep{ 
	#	$_ && !( $_ & 1 ) && not ++$seen{ $_ } 
	#} @{ $self }[ $start .. $end ];
}

1;

package main;

my $silly = SillyClass2->new( map $_ * 2, 1 .. 50 );
$silly->modifySubset( 15, 35 ) = ( 1 .. 20 ); ## should cause an error!