How to store arrays in hashes or objects?

From: Richard Heintze (sieg_heintze_at_yahoo.com)
Date: 10/29/03 

Date: Tue, 28 Oct 2003 20:40:07 -0800 (PST)
To: beginners@perl.org

I had emailed this query out previously but since I
never saw my own email in the digest, I'm assuming
that it never made it to the beginners@perl.org list.
Please forgive me if it did and I did not see it (my
SPAM filter might have eaten it).

Question #1
-----------
I have an array stored in an object and I trying to
compute the length of the array. This seemed to work
initially:

my $nColumns = $#{@{$me->{component_titles}}}+1;

Something changed, I don't know what, and perl started
dying on the above statement with no error message or
explanation. I had to resort to this technique:

my @ComponentTitles = @{$me->{component_titles}};
my $nColumns = $#ComponentTitles+1 ;

This seems to work, but I don't like it because it
uses a supefluous deep copy. Can someone tell me how
to do it in one statement without a superfluous deep
copy?

Question #2
-----------

Incidently, I believe I'm storing an array here
instead of a reference to an array.

I don't really do anything to create to create this
array -- I just start storing elements like this:

  $me->{component_titles}[0] = "xyz";

Is there a better way to populate this array? Perhaps
with a declaration or something?

Question #3
-----------

I tried to create a second array and store it by
reference like this:

my $a = [];
$me->{a} = \$a;
$a->[0] = 1;
$a->[1] = 23;
etc...

But when I tried to retrieve the array, there was
nothing there:

print $me->{a}->[0];

I cured the problem by storing elements directly, but
I did not want to make a new copy of the array (I
wanted to store a reference to the original array).

  $ii = 0;
  $me->{a}->[$ii++] = $_ foreach (@{$a});

Why does not this work:
 $me->{a} = \$a;

  Thanks,
         Siegfried

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