in reply to Checking for "return undef"

sub load_session {
...
        return undef;
...
}

And now consider my code: 
...
    $sid =  $cookies->{license_session}->value();

    # load session from db
    my $s = Mapps::Session->new();
    $s->load_session($sid);

    # session is good continue
    if (defined $s){
        $m->call_next;
    }

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return controls what the sub returns, but you aren't using a return value. load_session isn't ever going to change $s. Try: 
if (defined $s->load_session($sid)) {
   $m->call_next;
}

[download]
(Actually, a method can change the object it is called on, by assigning to $_[0]. This came as a surprise to me.)

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Re: Re: Checking for "return undef"
by Ovid (Cardinal) on Apr 21, 2004 at 16:33 UTC

    Actually, a method can change the object it is called on, by assigning to $_[0]. This came as a surprise to me.

    That's because @_ contains aliases to the passed arguments. It can be useful, but it's dangerous :)

    Cheers,
    Ovid

    New address of my CGI Course.

[reply]
      I know about the aliasing; I just assumed that the object passed was a shallow copy rather than the real McCoy.
[reply]

        I recall being surprised that $_[0] was a shallow copy and that assigning to $_[0] didn't change (the scalar holding) the object that invoked the method. I recall this being discussed in a node here (a while ago). I recall being surprised to hear the opposite (more recently but still at least weeks, probably months ago).

        So I think there used to be protections (perhaps unintentional) against modifying $_[0] in a method call and a while ago Perl changed in this regard.

        Sorry, I was unable to find hard references in the time allotted. I hope the wild rumors prove of some use anyway.

        - tye        

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