Re: C like op= proposal

[lrk@pobox.com (Lance Kibblewhite)]

Tarjei T. Jensen wrote:

>Keith Thompson wrote:
>> I'm well aware that there's little or no chance of this being added to
>> some future version of Ada (which makes this whole thread somewhat
>> off-topic, I suppose).  I'm just saying that I like the idea, and I
>> wouldn't mind seeing it in some future language.
>
>So would I. I don't care much for [+-*/]= as I too think it is ugly.
>However using @ or a functional equivalent seems to be worthwhile. It
>may make some code much more readable than it would otherwise be. I
>don't know if safety critical applications would want to use it, but it
>would be simple to expand the @s before using the source.
>
>So count me in on those who prefer a := @ + 1; over a += 1;

Since we are counting :-), count me out.

There are two issues.

1) Indication of modification of the LHS, as opposed to replacement.

For this, I do prefer the '+=' approach.

2) A shorthand for reducing the possibility of error in duplicating
complex expressions.

For this, consider this situation:

   declare
      Exp1 : <whatever> renames <first complicated expression>
      Exp2 : <whatever> renames <second complicated expression>
   begin
      Exp1 := Exp2 - Exp1 / Exp2 + 1;
   end;

'Renames' is much more versatile. The use of a 'special' notation to
reflect the LHS only seems too specialized.