Ranges, constantly frustrating

[Regan Heath]

On Tue, 11 Feb 2014 19:16:31 -0000, Steven Schveighoffer  
<schveiguy at yahoo.com> wrote:

> On Tue, 11 Feb 2014 05:10:27 -0500, Regan Heath <regan at netmail.co.nz>  
> wrote:
>
>> Things like this should "just work"..
>>
>> File input ...
>>
>> auto range = input.byLine();
>> while(!range.empty)
>> {
>>    range.popFront();
>>    foreach (i, line; range.take(4))  //Error: cannot infer argument  
>> types
>>    {
>>      ..etc..
>>    }
>>    range.popFront();
>> }
>>
>> Tried adding 'int' and 'char[]' or 'auto' .. no dice.
>>
>> Can someone explain why this fails, and if this is a permanent or  
>> temporary limitation of D/MD.
>
> This is only available using opApply style iteration. Using range  
> iteration does not give you this ability.
>
> It's not a permanent limitation per se, but there is no plan at the  
> moment to add multiple parameters to range iteration.
>
> One thing that IS a limitation though: we cannot overload on return  
> values. So the obvious idea of overloading front to return tuples of  
> various types, would not be feasible. opApply can do that because the  
> delegate is a parameter.

Thanks for the concise/complete response.  I had managed to piece this  
together from other replies but it's clearer now.

R

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