Re: array of hashes?

[marinersk]

Definitely read perldsc as per toolic's advice.

However, your question doesn't seem to match the title; or at least, I'm slow enough without my first cup of coffee this morning that I don't see how you're heading anywhere near an Array of Hashes (hereafter, AoH) with your problem.

Therefore, at the end of this post, I will give you a working example of an AoH in hopes that this will bridge the gap. Absent that, the conversation will hopefully lead us in a useful direction.

What your last paragraph and code suggest is that you are heading toward continued use of your hash as it exists, merely changing the keys based on a switch.

The purpose of an array is to have a list (no pun intended) of items which are simply stacked up and conveniently accessed. Traditionally accessed via their index value ([0] through [n]), Perl stepped up and gave us an indexless way to work through the queue in its most common use case: Sequentially processing each element. Perl's genius addition was the foreachloop.

So an Array of Hashes is a way to stack up a bunch of hashes in one place so they can be accessed without particular attention to how many of them there are, where they can later be processed (likely in a foreach loop).

I am really not making the connection between your description and the need to track multiple hashes from a single point.

Can you clarify? Or is it possible that AoH isn't exactly what you were looking for?

In the meantime, here's a sample use of AoH:

#!/usr/bin/perl

use strict;
use warnings;

# An example of using an array of hashes
my    @MasterArray = ();
my    %SubHash1 =
(
    'ABC' => 2,
    'DEF' => 3,
);
my    %SubHash2 =
(
    'GHI' => 5,
    'JKL' => 6,
);
my    %SubHash3 =
(
    'MNO' => 8,
    'PQR' => 9,
);

# Now use push to append a reference to the hash into the array:

push @MasterArray, \%SubHash1;
push @MasterArray, \%SubHash2;
push @MasterArray, \%SubHash3;

# Extract the reference and build a temporary hash to access its eleme
+nts:

foreach my $ArrayElement (@MasterArray)
{
    print "-----[ New Hash from Array ]---------------\n";
    my %CurrentHash = %$ArrayElement;
    foreach my $CurrentKey (sort keys %CurrentHash)
    {
        my $CurrentValue = $CurrentHash{$CurrentKey};
        print "Key {$CurrentKey} contains '$CurrentValue'\n";
    }
}
print "-------------------------------------------\n";

exit;

__END__

C:\Steve\Dev\PerlMonks\P-2013-10-27@0815-Array-of-Hashes>perl testAoH.
+pl
-----[ New Hash from Array ]---------------
Key {ABC} contains '2'
Key {DEF} contains '3'
-----[ New Hash from Array ]---------------
Key {GHI} contains '5'
Key {JKL} contains '6'
-----[ New Hash from Array ]---------------
Key {MNO} contains '8'
Key {PQR} contains '9'
-------------------------------------------