getNext

[Andrei Alexandrescu]

I think I figured out a comfortable and all-encompassing means to define 
a simplified interface for an input range.

Currently input ranges need to define empty, front, and popFront. That 
works but it's a bit heavy for simple input ranges. We've been 
discussing simplified interfaces in this group but couldn't find one 
that satisfied all use cases.

Consider this:

T* getNext(R, T)(ref R range, ref T item);

Semantics: if the range wants to expose addresses of its elements, it 
returns a pointer to the current element and also advances to the next 
element. Otherwise (i.e. the range does not have or does not want to 
expose addresses of its elements), the range fills "item" with the 
current value, again moves on to the next value, and returns &item.

In all cases, when there are no more elements in the range, getNext 
returns null.

getNext is easy to define for e.g. arrays and files. How does it sound? 
Does it bring significant simplification?


Andrei