Need a little help to expand my understanding of somewhat complex data structures. 
use strict;
my $hash_ref = {
    key1 => "value1",
    key2 => "value2",
    ary1 => [
        { ary_key01 => "ary_value01", ary_key02 => "ary_value02", },
        { ary_key11 => "ary_value11", ary_key12 => "ary_value12", },
    ],
};

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Given the above, I now wish to add (or edit) some values. For that I use this working solution. 
$hash_ref -> { key1 } = "new value1";
$hash_ref -> { key3 } = "add value3";
$hash_ref -> { ary1 }[2] = { ary_key21 => "ary_value21", ary_key22 => 
+"ary_value22", };

use Data::Dumper;
print Dumper($hash_ref);
exit;

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What I do not understand is how to make the above work with some sort of a data structure. Kind of like this.. 
$hash_ref -> {
    key1 => "new value1",
    key3 => "add value3",
    ary1[2] => [{ ary_key21 => "ary_value21", ary_key22 => "ary_value2
+2", }],
};

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Which gives errors:
Can't use subscript on constant item at test.cgi line 15, near "2]"
Can't use bareword ("ary1") as an ARRAY ref while "strict refs" in use at test.cgi line 15.

Can I do what I'm asking or should I stay with my initial approach?. A seach of PM and Perl Cookbook was little help.

In reply to Add values to a referenced HoH by nedals

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