#!/usr/bin/env perl
use 5.010; use strict; use warnings;
# a closure over a hash which takes a key as an argument and returns two subs
# which return the key and its value from the hash

sub get_caller {
    my $h = shift;
    return { parameter => sub {
                 my $k = shift;
                 my $v = $h->{$k};
                 return { name => sub { return $k },
                          val  => sub { return $v } };
             }
         };
}
my $c = get_caller( {'a.x' => 1, 'b.y' => 2, 'c.x' => 3} );
print $_->{name}(), ' : ', $_->{val}(), "\n" for $c->{parameter}('a.x');