package Foo;

use strict;
use warnings;
use Carp;

sub new{
	my $class = shift;
	my %args = @_;
	my $self = bless{}, $class;
	return eval{
		croak "x ist nicht gesetzt" if not exists $args{x}; 	
		$self;
	};
}



package main;

use strict;
use warnings;

my $f = Foo->new(xx => 1) or die $@; # Zeile 24