Re: Best way to manage refs in C + Garbage collection in a single collectgarbage() call.

["Mauro Iazzi" <mauro.iazzi@...>]

I had the same problem using Qt. I solved it using the environment to
store a method which is called by __gc on collection. It is that
method that contains the destructor if needed. With some __newindex
work you can
widget.__gc = widget.delete -- take ownership of widget
widget.__gc = nil -- don't destruct if collected
different functions could do this automatically. In your case
addWidget would release.

This assumes you don't actually need to also track the instances. In
the Qt case I have wrappers around functions that return children.

For the other problem, since I just used a userdata containing a
pointer, the destructor just zeroes this. Other functions will see
that as a NULL pointer. If you are wrapping some API you should add
the check to the wrappers. The gc will collect when it is more
appropriate without interfering with destructors.

mauro

2008/7/24 Michael Ferenduros <mike.ferenduros@gmail.com>:
> I guess you need to make the relationship a more explicit to the GC. Maybe
> storing a table of all member-widgets in the container's env-table would do
> the trick.
> You could alternatively do something equivalent with a semi-weak table
> stashed away in the registry (but possibly not if a widget can belong to
> multiple containers).
>
> Mike
>
>
>> So, two questions arise:
>> 1) Is there a better way to manage refs in C++ than the way I'm doing it?
>> 2) Is there a way to do this so that everything gets collected in the same
>> call to collectgarbage()?
>
>