Hello Monks.

I was looking at this perl.com article and I didn't understand how to interpret some of the syntax used: 
sub access_check
  {
    my $user_id     = shift;
    my @allow_users = @_;

    my %quick_allow = map { $_ => 1 } @allow_users;

    return $quick_allow{ $user_id };
  }

[download]

What is the map function doing? It effectively iterates through the array (storing each item in $_) and assigns a value of '1' to each? This results in an overall value of true? Zero would have been treated as false and the user wouldn't have been added to the array of allowed_users? Is this right?

I am also struggling to understand how to dereference code like this: 
my %ALL_USER_GROUPS = (
                    23 => [ qw( g1  g4 ) ],
                    13 => [ qw( g3  g5 ) ],
                    );

[download]

With so many braces, brackets, parentheses, etc., it quickly becomes difficult to interpret the meaning of the code. Is there a strategy I should routinely employ? How does one name such complex structures? A hash of hashes of arrays? In naming that complex data structure, would I start with the %ALL_USER_GROUPS hash and then move to the right (looking at the numeric keys) before looking at the anonymous arrays)?

When dereferencing complex data structures, where do I start? How do I know when a reference ends and when to add another curly brace or sigil?

Thanks Monks.

In reply to Need help with perl syntax. by Anonymous Monk

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