How to iterate using foreach on a class?

[Nicolas Sicard]

On Friday, 1 November 2013 at 12:37:20 UTC, simendsjo wrote:
> On Friday, 1 November 2013 at 11:41:52 UTC, Jonathan M Davis 
> wrote:
>> On Friday, November 01, 2013 12:30:10 Gary Willoughby wrote:
>>> I have a class which contains an array as a core collection of
>>> data. I want to pass an instance of this class to a foreach 
>>> loop
>>> and iterate through the enclosed array. How do i do this? I've
>>> asked this before and got an answer but i can't find anything 
>>> now.
>>
>> In general, if you want to make something work with foreach, 
>> you either make
>> it a range, or you give it an opSlice which returns a range 
>> (another
>> alternative would be define opApply, but in general, code 
>> should be using the
>> range primitives rather than opApply). Given that you're 
>> looking to iterate an
>> array, and you presumably don't want the array to be consumed 
>> when iterating,
>> the simplest would be to simply declare an opSlice on the 
>> class returns the
>> array. e.g.
>>
>> class C
>> {
>>    int[] foo;
>>    auto opSlice() { return foo; }
>> }
>>
>> Then when you use the class in a foreach loop, it'll be 
>> sliced, and the return
>> value of opSlice (the array in this case) will then be 
>> iterated over.
>>
>> - Jonathan M Davis
>
> So we basically have 4 ways..?
> 1) popFront + front
> 2) opSlice
> 3) alias this
> 4) opApply

How about having a nested struct implementing a range interface + 
a method (@property) returning it + alias this on the property?

http://dpaste.dzfl.pl/230061d2