On Tuesday, 28 July 2015 at 21:25:23 UTC, Ivan Kazmenko wrote:
Hello,
I wrap an array into a struct. Then I use alias this to expose
the array functionality. Sadly, range properties of the array
are not forwarded, and so I can't use the struct as an array
with functions from std.algorithm and std.range.
-----
import std.range, std.stdio;
struct S {
int[] contents;
alias contents this;
}
void main() {
S s;
writeln(hasSlicing!(S)); // false
}
-----
I would like to be able to do that, however.
1. Why exactly hasSlicing (et al.) does not check the alias
this-ed array when it checks the struct?
2. What should I do?
The solution I can think of is to insert the 3-6 range
functions which forward the functionality to the underlying
array, perhaps as a mixin.
Ivan Kazmenko.
`hasSlicing` explicitly checks whether the result of the slice
operator has the same type as the original:
https://github.com/D-Programming-Language/phobos/blob/master/std/range/primitives.d#L1499-L1500
If you remove the `static assert()` and change the next line to
use `auto`, and do the same in the other two places in this
templates, it will work.
I don't know whether this is intentional. I'd say we should allow
a sliceable range to have slices of a different type.
EDIT:
The documentation even says that it's intentional, but gives no
justification.
