how does isInputRange(T) actually work?
Ali Çehreli via Digitalmars-d-learn
digitalmars-d-learn at puremagic.com
Tue Apr 21 14:20:23 PDT 2015
On 04/21/2015 12:06 PM, kevin wrote:
> enum bool isInputRange = is(typeof(
> (inout int = 0)
> {
> R r = R.init; // can define a range object
> if (r.empty) {} // can test for empty
> r.popFront(); // can invoke popFront()
> auto h = r.front; // can get the front of the range
> }));
>
>
> ... is the current implementation in Phobos. But I can't seem to
> understand this syntax. What is (inout int = 0)? Why can a block follow it?
>
> My guess is that this is declaring some sort of function and testing if
> it is syntactically valid, but this is still strange to me.
I try to explain that syntax here:
http://ddili.org/ders/d.en/templates_more.html#ix_templates_more.named%20template%20constraint
Ali
More information about the Digitalmars-d-learn
mailing list