Should the comma operator be removed in D2?

[Stewart Gordon]

Yigal Chripun wrote:
> Stewart Gordon wrote:
>> Yigal Chripun wrote:
<snip>
>>> a + 5, b + a //
<snip>
> I don't follow you. What I said was that if you have the above in a for 
> loop with a comma expression, you'd expect to *first* add 5 to a and 
> *then* add the new a to b (comma operator defines left to right order of 
> evaluation).
<snip>

What "new a"?  Normally, the expression "a + 5" doesn't alter the value 
of a at all.  The only time it would is if a is of a programmer-defined 
type that has an opAdd function that does otherwise.  Such semantics 
bending is bound to create more confusion than the comma operator.

> tuples in general do not have to require a specific order since you keep 
> all the results anyway, so the above could break. by defining tuples to 
> be evaluated with the same order, the problem would be solved.

Forcing an evaluation order on tuples would preclude common 
subexpression optimisation.

Stewart.