Should the comma operator be removed in D2?

[grauzone]

Bill Baxter wrote:
> On Mon, Nov 16, 2009 at 2:04 PM, Justin Johansson <no at spam.com> wrote:
>> Mentioned in the switch case statements thread, this probably should be a
>> separate discussion thread.
>>
>> Is the comma operator "another piece of C cruft" that needs to be removed
>> from D(2)?
>>
>>
>> grauzone wrote:
>>> Justin Johansson wrote:
>>>> bearophile wrote:
>>>>> What's bad about forcing people to write:
>>>>> case A, B, C:
>>>>>
>>>>> Instead of:
>>>>> case A:
>>>>> case B:
>>>>> case C:
>>>>> ?
>>>>>
>>>>> Bye,
>>>>> bearophile
>>>> I don't know about "forcing people" to write such but perhaps it could
>>>> be an "option for people" :-)
>>>>
>>>> Actually I quite like the brevity you propose but would it be a
>>>> challenge for the comma operator?
>>>>
>>>> While ago, I got D multi-dimensional array syntax messed up and
>>>> declared such an animal as
>>>> int[3,4,5] which effectively ended up declaring the beast as int[5].
>>> The comma operator is another piece of C cruft that needs to go.
> 
> 
> Note that if comma-as-sequencer was removed, and repurposed as a tuple
> literal  (with "a,b"  making a tuple), and if we specify that tuple
> elements are evaluated in order, then I think this would work as a
> replacement for the current comma operator:
> 
>   (expr1,expr2,expr3)[$-1]
> 
> But the nice thing is you can get the effect of a comma operator that
> evaluates to the value of any expression in the sequence, just using
> different indices.
> Not sure how odious people would find forcing an order of eval on
> tuples, though.
> 
> In the context of a for-loop, you don't care what the value is, so it
> would work as a tuple as-is.  The tuple itself would be the value:
> 
>   for(; i<10; ++i,++j)  // just works

That's nice.

> Though, probably this case needs some special treatment to continue working:
> 
>   int i=0,j=0

Does it need to be a special case? "int i=0,j=0" is one declaration 
(with variables separated by a comma), not something glued together with 
the comma operator.

Of course normal declarations like "int i, j;" also would continue to 
work. Not all commas are part of a comma expression.

> --bb