in reply to Dereferencing an array of hash references

Two things come to mind. First, in building @loop, there is no need to dereference, and then rereference your anon hash. Just use 
foreach my $key (sort keys %sessions) {
    push @loop, $sessions{$key};
}

[download]
Second, db_retrieve_records returns an array reference \@loop, but you assign it to an array: 
my @loop = db_retrieve_records();

[download]
which is probably the cause of the error. A simple solution is to return the array: 
return @loop;

[download]
-Mark

Replies are listed 'Best First'.
Re: Re: Dereferencing an array of hash references
by fuzzyping (Chaplain) on Jun 26, 2002 at 19:48 UTC
    In response to your first, I'm going strictly by the example provided by the author of HTML::Template. If it's good enough (or required) by them, it's good enough for me.

    Second, attempts to return it NOT in the form of an array ref result in errors. As I mentioned, this data structure works fine for my other subroutine. The array is initiated and assigned *exactly* like it is in mail(), and then passed to the template object in the form of an array. No problems whatsoever.

    -fuzzyping
[reply]
      In that case, you need to properly dereference what you're getting back from db_retrieve_records. 

              my @loop = db_retrieve_records();

      [download]

      should be 

              my @loop = @{ db_retrieve_records() };

      [download]

      Also, you need to learn the difference between my and local.

      UPDATE
      Fixed a typo.

[reply]
[d/l]
[select]
        First, I'd like to thank you very much for solving the deref. That did in fact solve the problem with my data structure. However, I would like to know why you're inferring that I don't know the difference between my and local. Perhaps I've used an instance improperly, but I do know the differences and (supposedly) when to use them. I've locallized my scope where possible, and, where impossible, used local to allow scope to continue on to called subroutines.

        Would you mind elaborating? I'm not claiming to be right, but I sure don't know unless you give me a bit more detail as to your criticism.

        Either way, thanks again! :-)

        -fuzzyping
[reply]
      Perhaps there is a confusion. Your subroutine db_retrieve_records returns a reference to the @loop array, not the @loop array itself. If that is the return value you want for db_retrieve_records, then the mail routine needs correcting.

      First, save the reference to @loop: 
      my $loop = db_retrieve_records();

      [download]
      Then access loop information with the -> dereferencing op: 
      for my $i (0..@$loop-1) {
    foreach (qw( action type domain priority target )) {
        $body .= $loop->[$i]{$_};
    }
    $body .= "\n";
}

      [download]
      Note also that I used @$loop-1 for the last element of the outer loop.

      UPDATE: Mr. Freidman's is a much simpler fix. Consider mine as an alternative way to do it :)

      -Mark
[reply]
[d/l]
[select]
        Simpler, but not identical. Remember that when you say @{ $array_ref } you are making a copy of the array referenced by $array_ref. So your solution is certainly more efficient, in that you are accessing the original array and not making any copies, but it might be somewhat disastrous if you don't want to modify the original array.
[reply]

In Section Seekers of Perl Wisdom