Range Type

[Bill Baxter]

Janice Caron wrote:
> On 24/03/2008, Craig Black <cblack at ara.com> wrote:
>> I still think we don't need that second type.  We are talking about D 2.0,
>>  so backwards.compatibility is less of an issue.  Unless there's a compelling
>>  reason for it, it should be opSlice(T, T).  I think this makes more sense,
>>  and simplifies the syntax.
> 
> I agree.
> 
> But just to be sure, let's ask the loyal readers of this newsgroup...
> Has anyone here ever used opSlice(T,U), where type T != type U? And if
> so, for what purpose, and could you live without it?

Yes I have.  The purpose is to implement custom end-relative ranges. 
The end-relative indexes are represented using a struct like so:

struct EndRelative
{
    int offset;
}

That plus the __opDollar lets you make your user type accept x[3..$-2].

(And even without the opDollar harck you can make it work with something 
like x[3..end-2].)

--bb