[DGD] What are lightweight objects good for?

[Par Winzell]

> I have read about lightweight objects and understand what they do, but I 
> don't see how they are useful. Do they use less memory? I take it that's 
> what the 'lightweight' is about. Where would I want to use a lightweight 
> object rather than a regular object?

Traditional, 'heavy' objects have a permanent existance of their own.
They will stay around explicitly destructed. LWO's are light in that
when the last reference to them disappears, so do they -- at that point,
there's no way to ever reacquire a pointer to them.

With DGD, the main reason not to use LWO's for everything is that they
have a lot of limitations. If they had no limitations, you'd have a Java
style environment where -all- objects are garbage collected when their
last reference disappears, and where you e.g. run daemon threads (which
count as references) if they should lead self-sufficient lives.

In DGD, the best first use of LWO's is to replace all your old hacks
where you use arrays and mappings to represent what really ought to be
abstracted data structure. Most LPMuds that are 'grown up' versions of
2.4.5 have a lot of these around... fooConfig[FOO_CONF_FLAGS] &
FOO_FLAG_HUNGRY and such where you really should have
fooConfig->is_hungry(). Once you've completed a few rewrites like that,
you have a much better feel for what they can do.

After that, use them any time you want to be able to tie data and logic
in a single bundle that you can easily pass around, but which you don't
need to worry about destructing afterwards. If you're used to Java or
so, it should be completely natural.

For me, what happened was that I found myself trying to increasingly
simulate LWO's with 'heavy' objects. I'd put in little self-destructing
zero second callouts in objects that I wanted to be able to clone and
forget about. When LWO's came out, they were the answer to many a
prayer.

Zell


_________________________________________________________________
List config page:  http://list.imaginary.com/mailman/listinfo/dgd