Re: proposal for new assignment operators

[18k11tm001@sneakemail.com (Russ)]

Bill Findlay <yaldnifw@blueyonder.co.uk> wrote in message news:<BB1FBA16.36FD%yaldnifw@blueyonder.co.uk>...
> On 25/6/03 07:23, in article
> bebbba07.0306242223.1f86b3f7@posting.google.com, "Russ"
> <18k11tm001@sneakemail.com> wrote:
> 
> > One of the problems with adding these operators to Ada is that "/=" is
> > already used for "not equals." So I suggested that the Ada version of
> > these operators could be ":+", ":-", ":*", and ":/". I did not get
> > much of a reply, but I think it's an idea worth considering, so I am
> > repeating it here.
> > 
> > These operators would be consistent with the ":=" assignment operator
> > of Ada, and I don't think they conflict with any established Ada
> > operator. I actually think they make *more* sense than the usual "+="
> > type operators. Consider, for example,
> > 
> >   count :+ 1
> >   EulerAngles :* D2R
> > 
> > I'm wearing my asbestos underwear, so have at it!
> 
> Russ, you missed the point of my previous reply to this proposal.

Yes, I did.

> Your syntax is *in*compatible with the co-existence of the '=' operator and
> the ':=' assignment symbol. In your proposal, x :? y,
> for some operator ?, means: "x is assigned the value of (x ? y)".
> 
> I now ask, what does a := b mean when a and b are Boolean?
> Does it assign (a = b) to a, or does it assign b to a?

Oh, now I see what you mean. You have an interesting point, but I
don't think its particularly compelling. The ":=" symbol obviously
should not be redefined for this special case. So the answer to your
question is that a := b would assign b to a.

It's not really an incompatibility; its just that "=" doesn't happen
to be one of the operators that should have an in-place counterpart.
It wouldn't be useful anyway. After all, none of the languages with
"+=" have "===", do they?