On Saturday, 1 November 2014 at 13:22:34 UTC, Nordlöw wrote:
> On Saturday, 1 November 2014 at 11:45:25 UTC, Nordlöw wrote:
>> So why isn't something like x.stealFront already in Phobos?
>
> First try here:
>
> https://github.com/nordlow/justd/blob/master/range_ex.d#L14
>
> Please comment!

That is:

> auto ref stealFront(R)(ref R r)
> {
> import std.range: moveFront, popFront;
> auto e = r.moveFront;
> r.popFront;
> return e;
> }

`auto ref` is nonsense here. You can't return a reference to `e`
as
it's a local variable.

On Saturday, 1 November 2014 at 13:25:03 UTC, Nordlöw wrote:
> On Saturday, 1 November 2014 at 13:22:34 UTC, Nordlöw wrote:
>> https://github.com/nordlow/justd/blob/master/range_ex.d#L14
>>
>> Please comment!
>
> What's the recommended way of making stealFront and stealBack inout here? Can I somehow use auto ref together with inout?

I don't see what you'd need inout for here. stealFront/stealBack are not methods.

On Saturday, 1 November 2014 at 13:30:16 UTC, anonymous wrote:
> On Saturday, 1 November 2014 at 13:22:34 UTC, Nordlöw wrote:
>> On Saturday, 1 November 2014 at 11:45:25 UTC, Nordlöw wrote:
>>> So why isn't something like x.stealFront already in Phobos?
>>
>> First try here:
>>
>> https://github.com/nordlow/justd/blob/master/range_ex.d#L14
>>
>> Please comment!
>
> That is:
>
>> auto ref stealFront(R)(ref R r)
>> {
>> import std.range: moveFront, popFront;
>> auto e = r.moveFront;
>> r.popFront;
>> return e;
>> }
>
> `auto ref` is nonsense here. You can't return a reference to `e`
> as
> it's a local variable.

It's probably intended to mean `auto` + `ref`, not `auto ref`. `ref` alone is already sufficient to get type deduction.

On Saturday, 1 November 2014 at 13:25:03 UTC, Nordlöw wrote:
> On Saturday, 1 November 2014 at 13:22:34 UTC, Nordlöw wrote:
>> https://github.com/nordlow/justd/blob/master/range_ex.d#L14
>>
>> Please comment!
>
> What's the recommended way of making stealFront and stealBack inout here? Can I somehow use auto ref together with inout?

If you want to avoid the temporary variable, you could write:

    scope(success) r.popFront;
    return r.moveFront;

On Saturday, 1 November 2014 at 13:36:05 UTC, Marc Schütz wrote:
> On Saturday, 1 November 2014 at 13:30:16 UTC, anonymous wrote:
[...]
>>> auto ref stealFront(R)(ref R r)
>>> {
>>> import std.range: moveFront, popFront;
>>> auto e = r.moveFront;
>>> r.popFront;
>>> return e;
>>> }
[...]
> It's probably intended to mean `auto` + `ref`, not `auto ref`. `ref` alone is already sufficient to get type deduction.

But ref is wrong. The function returns a local. Just auto would
be fine.

On Saturday, 1 November 2014 at 13:38:22 UTC, Marc Schütz wrote:
> If you want to avoid the temporary variable, you could write:
>
>     scope(success) r.popFront;
>     return r.moveFront;

Does this solution cost performance?

On Saturday, 1 November 2014 at 13:30:16 UTC, anonymous wrote:
> `auto ref` is nonsense here. You can't return a reference to `e`
> as
> it's a local variable.

My mistake. Thanks.

On Saturday, 1 November 2014 at 13:36:05 UTC, anonymous wrote:
> I don't see what you'd need inout for here. stealFront/stealBack are not methods.

inout can be used on free functions aswell. See for example

https://github.com/nordlow/justd/blob/master/algorithm_ex.d#L674

On Saturday, 1 November 2014 at 13:38:22 UTC, Marc Schütz wrote:
> If you want to avoid the temporary variable, you could write:
>
>     scope(success) r.popFront;
>     return r.moveFront;

Nice solution anyhow! Thanks!

On Saturday, 1 November 2014 at 13:54:31 UTC, Nordlöw wrote:
> On Saturday, 1 November 2014 at 13:38:22 UTC, Marc Schütz wrote:
>> If you want to avoid the temporary variable, you could write:
>>
>>    scope(success) r.popFront;
>>    return r.moveFront;
>
> Does this solution cost performance?

I guess we have to look at the assembler output to be sure. Is there a convenient way to do this in LDC?