std.range.interfaces : InputRange moveFront

[Tony]

On Thursday, 30 November 2017 at 06:36:12 UTC, Ali Çehreli wrote:

>
> move is an operation that transfers the state of the source to 
> the destination. The front element becomes its .init value and 
> its previous values is returned by moveFront().
>
> The important bit is that, the element is *not* copied:
>
> import std.range;
>
> struct S {
>     int i;
>     bool is_a_copy = false;
>     this(this) {
>         is_a_copy = true;
>     }
> }
>
> void main() {
>     auto r =  [S(1)];
>
>     auto a = r.front;
>     assert(a.is_a_copy);       // yes, a is a copy
>     assert(a.i == 1);          // as expected, 1
>     assert(r.front.i == 1);    // front is still 1
>
>     auto b = r.moveFront();
>     assert(!b.is_a_copy);      // no, b is not a copy
>     assert(b.i == 1);          // state is transferred
>     assert(r.front.i == 0);    // front is int.init
> }
>

Thanks for the reply. Probably just missing it, but in poking 
around dlang.org (Language Reference and Library Reference) I am 
having trouble finding out about the move(), front() and 
moveFront() functions, as is used here on a dynamic array.