[pm-h] When to use "weaken"?

[Todd Rinaldo]

On Jan 24, 2014, at 8:44 AM, Michael R. Davis <mrdvt92 at yahoo.com> wrote:

>>> 
>>> If I'm understanding you, that's the definition of a circular reference.
>>> 
>>>      parent -> child -> parent
>> 
> 
> Can't locate object method "cfg" via package "XXX::Profiles::Profile" at /usr/lib/perl5/vendor_perl/5.10.0/XXX/Profiles/Profile.pm line 112.
>  
> So, weaken must not work like I think.  The child has lost the link to the parent.  I guess the child to parent link is more important than the parent to child relationship.  Maybe I need to weaken the parent ref.  Maybe as Todd suggested I need to re-think the architecture.
>  
> For now I'm going to exit after a few loops and restart on cron with Sys::RunAlone or something like that.
>  
> Maybe I need to use a DESTROY block and undef($self->{"parent"}) in it.  Anyone know the gotchas on DESTROY?
>  

weaken =~ “lower the reference count by one"

At a glance from the code I saw, you were weakening too much. The way that works is Perl keeps a count of all the things that point to a piece of information. When it drops to zero, the variable is destroyed. The code I saw had 2 occurrences of weaken. It’s likely you’ll need to carefully craft it so only one side weakens.