On 05/20/2018 10:46 AM, Robert M. Münch wrote:
> But I still don't understand why I can't write things explicitly but
> have to use an alias for this.
Templatized range types work well when they are used as template
arguments themselves.
When you need to keep a single type like 'b' (i.e. b is not a template),
and when you need to set a variable like mySubStream to a dynamic
object, the solution is to use inputObject():
import std.algorithm;
import std.range;
class a {
int[] myStream = [ 1, 2, 42, 100 ];
}
int myMessage = 42;
class b {
InputRange!int mySubStream;
}
void myFunc() {
a myA = new a();
b myB = new b();
myB.mySubStream = inputRangeObject(myA.myStream.filter!(x => x ==
myMessage));
assert(myB.mySubStream.equal([myMessage]));
}
void main() {
myFunc();
}
Now, mySubStream is a range variable that satisfies the input range
interface and produces int elements. (Adjust accordingly.) You can use a
more specialized range kind other than InputRange if the actual range
supports it (e.g. ForwardRange!int, etc.):
http://ddili.org/ders/d.en/ranges_more.html#ix_ranges_more.inputRangeObject
https://dlang.org/phobos/std_range_interfaces.html#inputRangeObject
Ali
