[DGD] Memory management

[Par Winzell]

>>I probably just need a pointer in the right direction, but I'm getting a 
>>bit confused on DGD's memory  management.
>>
>>My impression was that DGD used a reference counting scheme to free up 
>>objects that no longer had references, similar to Java's garbage collection.
>>
> 
> [...]
> 
>>What am I missing?
> 
> There are two types of objects, persistent (regular) objects, and the
> so-called lightweight objects a.k.a LWOs.  LWOs are created using the
> new_object() kfun and will disappear automatically, whereas regular
> objects are created using compile_object() for standalone objects and
> clone base-objects, clone_object() for clones, and zapped into
> oblivion using destruct_object().

To expand on this: for persistent objects (which is all you'll see in 
the kernel library) the references to the object are of no consequence; 
when the object is destructed, any existing reference to the object will 
evaluate to 'nil'. In a multi-programmer environment like your average 
LPMud, this is more than practical, it is more or less a requirement -- 
if every sloppy left-over reference could keep an object alive, there 
would be accrue vast unfreed and unused object structures in memory over 
the years.

As it is, this 'destruction' scheme allows you to go occasionally slowly 
sift through all the potentially millions of objects and crudely put the 
obsolete ones to death, automatically castrating any existing references 
to them.

Zell

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