use strict;
use warnings;

{
	package Base;
	our %types = qw/BASE_TYPE Some::Class/;
	sub get_type { $types{$_[0]} }
}

{
	package Foo;
	our @ISA = qw/Base/;
	$Base::types{FOO_TYPE} =  q/Another::Class/;
}

{
	package Bar;
	our @ISA = qw/Base/;
	$Base::types{BAR_TYPE} =  q/Yet::Another::Class/;
}
use Data::Dumper;
print Dumper \%Base::types;

print Base::get_type('BAR_TYPE'), $/;