[m-dev.] for review: a replacement of code_exprn.m

[Zoltan Somogyi]

On 17-Aug-2000, Fergus Henderson <fjh at cs.mu.OZ.AU> wrote:
> > It is always a bad idea to have two copies of a data structure:
> > you never know which one is authoritative.
> 
> I agree with the general principle.  However, in this case we can solve
> the problem by ensuring that they are always both authoritative.
> I think this is going to be a much simpler solution than the alternatives.

In the short term, yes. In the long term, no. My proposal requires more changes
up front: changing all the code of the compiler where you look up things in
the globals inside the IO state, instead of changing all the code of the
compiler that modifies the globals structure. However, it eliminates the
requirement for "double maintenance" of the globals structure. I think this
is a significant plus, since such double maintenance is highly error prone.

Zoltan.
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