About foreach loops

[Andrei Alexandrescu]

On 6/15/11 11:51 AM, KennyTM~ wrote:
> On Jun 15, 11 23:23, Caligo wrote:
>> On Wed, Jun 15, 2011 at 9:44 AM, KennyTM~<kennytm at gmail.com> wrote:
>>> On Jun 15, 11 22:35, Caligo wrote:
>>>>
>>>> You can create a temporary if you like:
>>>>
>>>> foreach(i; 0..10){
>>>> int ii = i + 1;
>>>> writeln(ii, " ");
>>>> }
>>>>
>>>> Which outputs:
>>>> 1 2 3 4 5 6 7 8 9 10
>>>>
>>>>
>>>> The problem with trying to "fix" foreach is that it would create
>>>> problems of its own. The following code would not behave correctly:
>>>>
>>>> foreach(i; 0..10){
>>>> if(i& 1)
>>>> i += 1;
>>>> writeln(i, " is even.");
>>>> }
>>>>
>>>> not to mention all the code that's already using foreach.
>>>
>>> If the code rely on the 'implicit ref' behavior of 'i', the code is
>>> doing it
>>> wrong. The spec never mentioned what happened when the variable is
>>> modified
>>> in a ForeachRangeStatement. I believe it is more sane if modifying
>>> 'i' is
>>> disallowed unless 'ref' is used.
>>>
>>
>>
>> This should be a compile time error:
>>
>> foreach(i; 0..10){
>> i += 1;
>> write(i, " ");
>> }
>>
>> This should be legal.
>> foreach(ref i; 0..10){
>> i += 1;
>> write(i, " ");
>> }
>>
>> Is that the general consensus here?
>
> A simple patch for this:
>
> https://github.com/kennytm/dmd/compare/master...const_foreach_range

Does that take care of change through an alias, e.g.

int * p = i;
++*p;


Andrei