Re: GC - again, :-)

["Nick Roberts" <Nick.Roberts@dial.pipex.com>]

Brian Rogoff <bpr@best.com> wrote in article
<Pine.SGI.3.95.970430110433.18224A-100000@shellx.best.com>...
> [...] since I've been writing an
> interpreter for a Lisp-like language in Ada. Obviously I can write a 
> GC for a set of objects as part of the interpreter proper, since I 
> know the lifetimes of many objects, and all of the roots, but I'd
> prefer to be able to say something like 
> 
> 	type SExpr_ID is access all SExpr_Type'Class;
> 	for SExpr_ID'Storage_Pool use Garbage_Collected_Pool;
> 	...
> 	-- These are ugly, but might be useful
> 	Register_Root ( Garbage_Collected_Pool, Root_1 );
> 	...
>         Register_Root ( Garbage_Collected_Pool, Root_n );
> 
> and thus be able to reuse the collector easily in other contexts. 


It seems to me that a representation clause would be the much the best way
to specify what sort of storage reclamation strategy is applied to a
storage pool. I would (quite strongly) suggest that full reclamation ought
to be the default, with agreed-upon clauses for selecting other strategies.
There would surely be an option No_Reclamation to switch garbage collection
off completely, for those occasions when it was required.

I would greatly appreciate opinions on this.

Nick.