Re: gnubol: Compiler Limits

[RKRayhawk@aol.com]

Concerning arbitrary limits of 64 EVAL subjects, and 256 E-WHEN clauses,
In a message dated 12/27/99 10:38:27 AM EST, migrate@tiac.net writes:

<< 
 I have yet to push that limit in my environments, but at least in the Wang
 VS/AIX/HPUX COBOL85 compiler there was no such limit, because the WHEN
 phrases were trees in the EVALUATE orchard.
 >>

That seems best if we can mimmick it. Yet at some point we acquire a right to 
be defensive of the compiler itself.  At some point it appears to be a 
monster, and we could have some resource weakness; such as compilable but not 
in reasonalble time due to virtual paging.

So maybe as a design idea we may want these to have parametric controls that 
allow really large subject/when arrangements by default, but not infinite. 
The user could then override the
defaulting parameter. 

This actually be inkeeping with the notion of giving the compiler as much 
feedback as we can on each compile (although it seems paradoxical at first).  
For real monster, in the absence of finite limits we might suffer either 
failure or such performance problems as to prompt kills. The user may then 
not really know why.  So the point of a defaulting finite limit would be to 
give them the threshold crossing signals: first you are nearing limits: 
condition yellow; second you are crossing limits: condition red.  They could 
then be asked to rerun with consciously specified limit overrides.

So the purpose of the defaulting finite limit(s) would be to increase the 
likelihood that as many useful diagnostics will get out in early attempts to 
compile monsters.

Are there other aspects of limits that we should think about before coding 
syntax / semantics so that we can see ahead of time where parametric devices 
might be considered early?

Best Wishes
Bob Rayhawk
RKRayhawk@aol.com






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