Sentinel InputRange ?

[Andrei Alexandrescu]

On 2/9/13 3:49 PM, Walter Bright wrote:
> On 2/9/2013 12:43 PM, Walter Bright wrote:> Perhaps we can formalize
> this a bit. Define a SentinelInputRange, which has an
>  > additional manifest constant with the name 'sentinel'. empty becomes
> defined as:
>  >
>  > empty = front == sentinel;
>  >
>  > popFront() does not advance if empty. Advancing over a
> SentinelInputRange can be
>  > done the usual:
>  >
>  > for (r = range; !r.empty; r.popFront()) { auto e = r.front; }
>  >
>  > or can be done as:
>  >
>  > for (r = range; r.front != sentinel; r.popFront()) { auto e = r.front; }
>
> If it's not clear, SentinelInputRange.front can be called *before*
> checking empty. If it is empty, then the sentinel is returned.

Yah, that all would fit C-style strings and singly-linked lists like a 
glove. I've been long hoping the opportunity to define such a range 
would present itself :o).

Andrei