Re: [Gnash-dev] Garbage collector

[Eric Hughes]

At 02:18 PM 6/15/2007, strk wrote:
> var o = new Object;
> o.hello = function() { trace("hello"); }
> Function.prototype.constructor = o;
> delete o;
> Function.prototype.constructor.helo(); // expect a trace

Two issues: the reference outward from "constructor" and the references 
toward "o".

First.  The reference variable for "constructor" should be able to be hold 
either a weak or a strong reference, and it would be initialized to a weak 
reference.  This means that in the ordinary case where constructor 
assignment does not occur, that the incremental RC mechanism will catch it, 
eliminating an item for the GC to deal with.

Second. After assignment, "constructor" (an l-value) contains a strong 
reference to the r-value of "o".  At this point both the variables "o" and 
"constructor" have references.  Then when the variable "o" itself goes away 
(an l-value), "constructor" still has a strong reference.

This was the kind of thing I mentioned earlier about possibility and 
feasibility.  To use weak references in this way requires that r-values and 
l-values be separate, and I'm just not familiar enough with the VM 
implementation to know if this is already there or, if lacking, what 
requisite effort would be resolved.

Eric