Re: Underscores in identifiers (was: Warning: Religious naming convention discussion :-)

[Ben Brosgol <brosgol@world.std.com>]

Robert A Duff wrote:
>  ...                            There were three separate votes taken
> (which I thought was silly), on three separate issues.  Whether to allow
> (1) leading underscores, (2) two underscores in a row, or (3) trailing
> underscores.  To my astonishment, the votes came out different.  I'm not
> too sure, but I think (2) lost by a little bit, (1) lost by a greater
> margin, and (3) won by a little bit.  So the design team published the
> next version of the document allowing (3).  However, this annoyed some
> people greatly.  It was more than just the French delegation.  So,
> although I had been in favor of free use of underscores, I pushed on
> Tucker to go back to the Ada 83 rule, because (A) I thought that it was
> ludicrous to change the rule, but not change it fully, and (B) although
> the split was roughly 50-50, the people against trailing underscores
> felt much more strongly (fanatically, I would say!) than the other side,
> so we shouldn't piss people off over such an unimportant feature.  So we
> proposed this at the next meeting, and that's the way it ended up.
> ...
> >Anyway, there you are -- it's not in Ada 95 (you can guess which side
> >Robert_ Dewar_ was_ supporting_ :-)
> 
> I was on the same side as Robert.  The really annoying thing is that we
> were trying to have a good interface to C, and *leading* underscores
> would come in really handy, there.
> 
> I suppose the design team could have insisted on having our way, but we
> wanted to save our insisting for cases we felt were important enough to
> go against the majority opinion.
> 
> - Bob

Let me add my recollections, since I guess I'm responsible for stirring
up the pot here with my earlier article.  At one point in the Ada 9X
design (I think this was in mid '93 or so) we had reached a grudging
compromise allowing an identifier to include a single trailing
underscore.  Just as the embers of this issue were dying down, a member
of the design team, Offer Pazy, came along with a figurative can of
gasoline and sent out a message to the reviewers to the effect that
allowing identifiers to end with an underscore was a violation of
fundamental Ada design principles, or something to that effect.  (Offer,
if you're out there and reading this, you can confirm or deny this
point.)  In any event, there's nothing like an argument about lexical or
syntactic issues to get people's language designer juices flowing  --
some would be amazed at how much time was spent at the Villars WG9
meeting (March '94) before settling on "Adjust" for the name of the
procedure that is invoked during assignment for a controlled type -- and
it wasn't long before it was obvious that the "compromise" solution for
a single trailing underscore was unraveling.  As Bob mentioned in the
quote above, the dynamic was that noone felt passionatley in favor of
allowing more generality for underscores in identifiers, but at least
one delegation (and I think others as well) felt _extremely_ strongly
that such liberalization would seriously compromise program
readability.  So back to the Ada 83 identifier rules we reverted.  

Ben Brosgol
brosgol@aonix.com