#!/usr/bin/perl

use strict;

my @firstlist = qw(1 2 3 4 5);
my @secondlist = qw(A B C D E);

process_list(\@firstlist);
process_list(\@secondlist);

sub process_list {
    my($list_ref) = @_;
    sub get_list { return @$list_ref; }

    print_list();
}

sub print_list {
    foreach my $item (get_list()) {
        print "LIST ITEM: $item\n";
    }
}
[download]

Output:

LIST ITEM: 1
LIST ITEM: 2
LIST ITEM: 3
LIST ITEM: 4
LIST ITEM: 5
LIST ITEM: 1
LIST ITEM: 2
LIST ITEM: 3
LIST ITEM: 4
LIST ITEM: 5
[download]

Why does the closure "get_list" not get updated to use the reference to @secondlist? I'm assuming there is a scope issue with the way "get_list" is declared. I understand there is a better way to write this with the use of a function that returns an anonymous sub but I'm not sure how to explain the issue with the code above. Better solution:

#!/usr/bin/perl

use strict;

my @firstlist = qw(1 2 3 4 5);
my @secondlist = qw(A B C D E);

process_list(\@firstlist);
process_list(\@secondlist);

my $get_list_sub;

sub make_list_closure {
   my ($ref) = @_;
   return sub { return @$ref; };
}

sub process_list {
    my($list_ref) = @_;

    $get_list_sub = make_list_closure($list_ref);

    print_list();
}

sub print_list {
    foreach my $item ($get_list_sub->()) {
        print "LIST ITEM: $item\n";
    }
}
[download]

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