On 11/29/2017 08:31 PM, Tony wrote:
What does the moveFront() method do in the InputRange interface?
std.range.interfaces : InputRange.moveFront()
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
}
Ali
