scope.pl

package Scope;

sub new {
  my $class = shift;
	my $hash = { v => 0 };
	$hash->{r} = "$hash";
	return bless $hash, $class;
}

sub txn {
	my $self = shift;
	my $sub  = shift;
	eval {
		print "start\n" unless ($self->{v});
		print "[", $self->{r}, "] ", $self->{v}, " => ";
		$self->{v}++;
		print $self->{v}, "\n";
		$sub->(@_);
		print "[", $self->{r}, "] ", $self->{v}, " => ";
		$self->{v}--;
		print $self->{v}, "\n";
		print "end\n" unless ($self->{v});
	};
	if ($@) {
		print "[", $self->{r}, "] ", $self->{v}, " => ";
		$self->{v}--;
		print $self->{v}, "\n";
		print "end\n" unless ($self->{v});
	}
}

package main;

my $scope = Scope->new();

$scope->txn(sub{
#	die "die";
	$scope->txn(sub{
#		die "die";
	});
#	die "die";
});

#my $scope1 = Scope->new();
#my $scope2 = Scope->new();
#
#$scope1->txn(sub{
#	$scope2->txn(sub{
#		die "die"
#	});
#});