At

https://github.com/nordlow/phobos-next/blob/master/src/moval.d

I've implemented a helper function for creating r-value out of l-values defined as

E movedToRvalue(E)(ref E e)
{
    import std.algorithm.mutation : move;
    E value;
    move(e, value);             // this can be optimized
    return value;
}

For the case when movedToRvalue is called with an r-value, such as in,

    static assert(__traits(compiles, { consume(S(14)); }));

I would like to overload to an identity op.

Is this currently possible somehow? I cannot find any trait `isRvalue` that fulfills

    static assert(isRvalue!(S(14)));

Is there one?

On Monday, 10 October 2016 at 11:46:01 UTC, Nordlöw wrote:
> Is there one?

Found it:

http://forum.dlang.org/post/n8m8bh$2vgc$1@digitalmars.com
https://issues.dlang.org/show_bug.cgi?id=15634

On Monday, 10 October 2016 at 11:51:09 UTC, Nordlöw wrote:
> Found it:
>
> http://forum.dlang.org/post/n8m8bh$2vgc$1@digitalmars.com
> https://issues.dlang.org/show_bug.cgi?id=15634

Ok, so I added `isLvalue` and `isRvalue` to

https://github.com/nordlow/phobos-next/blob/master/src/moval.d

Now the next follow-up question becomes how to use it to restrict/overload my definition of `movedToRvalue()` since `isLvalue` takes an alias as argument and `movedToRvalue` takes a reference to an instance. How to solve this?

On Monday, 10 October 2016 at 11:46:01 UTC, Nordlöw wrote:
> At
>
> https://github.com/nordlow/phobos-next/blob/master/src/moval.d
>
> I've implemented a helper function for creating r-value out of l-values defined as
>
> E movedToRvalue(E)(ref E e)
> {
>     import std.algorithm.mutation : move;
>     E value;
>     move(e, value);             // this can be optimized
>     return value;
> }
>

Doesn't the second overload of `move()` already do what you want?

https://dlang.org/phobos/std_algorithm_mutation.html#.move

Note that in your implementation, you needlessly initialize `value`, which then needs to be properly destroyed by `move()`, which the Phobos implementation avoids:

https://github.com/dlang/phobos/blob/master/std/algorithm/mutation.d#L1083-L1088

> For the case when movedToRvalue is called with an r-value, such as in,
>
>     static assert(__traits(compiles, { consume(S(14)); }));
>
> I would like to overload to an identity op.

If the compiler is smart enough to understand what `moveEmplace()` does, it could already do this automatically.

On Monday, 10 October 2016 at 12:22:54 UTC, Marc Schütz wrote:
>> I would like to overload to an identity op.
>
> If the compiler is smart enough to understand what `moveEmplace()` does, it could already do this automatically.

Doh! My mistake.

I'll use `moveEmplace`, then.

Thx!