in reply to Unblessed Reference Message

See the comments. A ref becomes an object after being blessed, as now Perl knows who/what it is. 
ap.pm:
package ap;

sub new {
    my $self = {};
    bless $self; #comment this will cause the error you described.
    return $self;
}

sub item_id {
    my $self = shift;
    if (@_) {
        $self->{ITEM_ID} = shift;
    } 
    return $self->{ITEM_ID};
}

1;

ap.pl:
use ap;
use strict;

my $a = new ap;
$a->item_id(10);
print $a->item_id();

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Update

So your code is more simple than I thought, there is no OO involved.

But the underlying mistake looks the same to Perl. As your syntax made Perl thought it was a method call, but the host is an unblessed ref.

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Re: Re: Unblessed Reference Message
by converter (Priest) on Jan 26, 2003 at 21:36 UTC

    A ref becomes an object after being blessed, as now Perl knows who/what it is.

    This is incorrect, and will eventually bite you in the rear end. From perlfunc: 

           bless REF,CLASSNAME
       bless REF
               This function tells the thingy referenced by
               REF that it is now an object in the CLASSNAME
               package...

    [download]

    It is the thing referred to, not the reference, that is blessed. This is why we can copy the reference returned by bless and still invoke methods against the reference--perl knows that the reference refers to an object of class class because it's the referent that is marked as belonging to a particular package.

[reply]
[d/l]
      Thank you for making what I said more formal, but to be honest, I mean exactly the same thing, and I didn't expect people to misunderstand it. (Or to be precise, you correctly understood what was on the screen word by word, but had the wrong expectation.)

      This is a good lesson, and I will try to make my wording more formal.
[reply]
Re: Re: Unblessed Reference Message
by b310 (Scribe) on Jan 26, 2003 at 21:18 UTC
    Thank you all. Problem eliminated.
[reply]

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