Re: gnubol: subsets

[RKRayhawk@aol.com]

In a message dated 11/20/99 12:14:30 PM EST, TIMJOSLING@prodigy.net writes:

<< 
 * Forward references make it difficult to do stuff as you go. 
>>


Again, strickly one man's point of view. But forward reference resolution is 
a piece of cake. If you don't know what they are talking about then just 
instantiate that in SYMT. Hang a note on that node every time it is 
referenced if it has not yet been resolved. Syntax itself can review SYMT, if 
it has nodes with hangers on that have never been resolved then, presto all 
of those lines get flagged. If it got resolved by being declared then the 
numerous pointers to that SYMT node that you handed to semantics will quietly 
be already resolved and functional, but semantics can see clearly if any SYMT 
node never got properly built, no matter how many references.

Syntax's review of this list of unresolved references is a little quicker if 
you make sublists to the head of each SYMT node that had 1 or more initially 
unresolved forward references. This list review is like a miniature pass, but 
it is comparatively smaller then a full pass. ((by the by once instantiated, 
the node nolonger needs additional notes about references because they become 
backward unremarkable references)).

Much of this problem simply vanishes if Preprocess supports SYMT in the 
procedure division. I am saying in that undertow that if we see a discernable 
procedure name in the the output buffer of the preprocess, it is basically 
unforgivable that we forget it. What forward reference?
((Actually the environment division has forward references too, some of those 
might vanish too if you drive SYMT early.  A compile is a compile, so build 
tables!  Like _early_. Real early)).

It is a classic technique to push forward references onto SYMT. This is 
syntax work, IMHO, not something to hand to semantics.

Best Wishes
Bob Rayhawk
RKRayhaw@aol.com





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