Can we get rid of opApply?

[Steven Schveighoffer]

"Daniel Keep" wrote
>
>
> Steven Schveighoffer wrote:
>> "Robert Fraser" wrote
>>> Steven Schveighoffer wrote:
>>>> The other possibly sensible reason to keep opApply is for
>>>> interfaces/classes.  Ranges as a class would be slower than even 
>>>> opApply,
>>>> as each loop iteration would call a virtual function.
>>> There would only need to be one vtable lookup for each function (since
>>> every iteration would use the same head(), next(), etc.) So it would be
>>> the same price as opApply (a function pointer call). Well, 3 times the
>>> price, since 3 functions need to be called.
>>
>> You could technically cache the vtable lookup, but a vtable call costs 
>> more
>> than a delegate call (one lookup for vtable, then function + pointer call
>> vs. just function + pointer call).  But besides that, yes, it would be 3
>> functions called per iteration.  So still slower...
>>
>> -Steve
>
> Add opRange and allow it to return a struct.

How do you define that in an interface?  You must pre-define the struct, 
which means the struct must have implementation details before the class is 
even written.

-Steve