#!/usr/bin/perl
use feature qw/say state switch/;
use strict;
use warnings;

sub gen_cashier {
    my ($start) = @_;
    state $cash_in_store = $start // 0;

    return sub {
        my ($method, $amount) = @_;
        given ($method) {
            when (undef) { warn "Method name required\n" }
            when ('add') { $cash_in_store += $amount }
            when ('del') { $cash_in_store -= $amount }
            when ('bal') { return $cash_in_store     }
            when (/^(?<name>[a-zA-Z]+)$/) { warn "$+{name} unimplemented\n" }
            default { warn "$method is illegal method name\n" }
        }
    };
}

my @drawer = map gen_cashier, 1..4;

$drawer[0]->(add => 59);
$drawer[1]->(del => 17);
$drawer[2]->(steal => 20);
say $drawer[3]->('bal');