[m-dev.] for review: add Mission Critical extensions

[Fergus Henderson]

On 06-Jul-2000, Simon Taylor <stayl at cs.mu.OZ.AU> wrote:
> 
> [Pete Ross wrote:]
> > Add the Mission Critical extensions to the compiler.  These extensions
> > are only turned on if --enable-mc is supplied to configure.
> > The point of this change is to minimize the diff between the Mission
> > Critical Mercury compiler and the Melbourne Mercury compiler.
> 
> Please add something here to explain why the Mission Critical version
> of the compiler needs to be different, and why these features can't be
> enabled by default.

Yes, what he said.  The revised diff does not address that review comment.

> Isn't this useful for users other than Mission Critical?

Pete, I don't think you really answered that question.

Now, in response to the rationale given in the log message:

> > The point of this change is to minimize the diff between the Mission
> > Critical Mercury compiler and the Melbourne Mercury compiler.

OK, this change does, no doubt, make that diff smaller.  And so
Mission Critical will have less work to do when merging in our changes.

But it does so at the expense of making the Melbourne Mercury compiler
more complicated: an extra layer of macros and conditional compilation.
This may well make the Melbourne Mercury compiler more difficult to
maintain.  And it seems that Mission Critical are the only users who
will benefit!

So, I would like to ask: is there a better way that we can do this?
Is there some way in which all Mercury users, rather than just Mission
Critical, could (at least potentially) get the benefit of this new feature?

If the answer is no, then I guess I'd still be willing to accept the
change, albeit somewhat grudgingly, because users of the language are
important to us, and Mission Critical is (at least currently) a very
important segment of Mercury's users.  But if the change such that
it adds complexity in a way that means Mission Critical is the only
group that can really take advantage of that complexity, then I think
we should at very least impose extremely scrupulous documentation
standards before accepting such a change.

So, in summary, the code for this change looks fine, but I'm not yet
happy with the rationale, log message, and documentation.
I'd like to see another diff.

Cheers,
	Fergus.

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh>  |  of excellence is a lethal habit"
PGP: finger fjh at 128.250.37.3        |     -- the last words of T. S. Garp.
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