auto ref

[Simen kjaeraas]

On Thu, 17 Dec 2009 17:26:52 +0100, Leandro Lucarella <llucax at gmail.com>  
wrote:

> Simen kjaeraas, el 17 de diciembre a las 02:16 me escribiste:
>> On Wed, 16 Dec 2009 12:00:46 +0100, KennyTM~ <kennytm at gmail.com> wrote:
>>
>> >On Dec 16, 09 15:18, Walter Bright wrote:
>> >>There's a need in generic code to have a function take a parameter by
>> >>ref if it is an lvalue, and by value if it is an rvalue. This can be
>> >>addressed by making it a template using auto ref:
>> >>
>> >>T foo(T)(auto ref T x) { ... }
>> >>
>> >>foo(3) // call by value
>> >>int y;
>> >>foo(y) // call by reference
>> >>
>> >>There is also a need to 'transmit' the ref'ness to the return value.
>> >>This can be done with auto ref:
>> >>
>> >>auto ref foo(T)(auto ref T x) { return x; }
>> >>
>> >>foo(3) => int foo(int x)
>> >>foo(y) => ref int foo(ref int x)
>> >>
>> >>This means that the generic forwarding function would look like:
>> >>
>> >>auto ref foo(alias F, T...)(auto ref T args) { return F(args); }
>> >
>> >auto const?
>>
>> auto const auto ref Foo bar( auto const auto ref Foo arg ) {
>>     return arg;
>> }
>>
>> Am I the only one who finds this confusing?
>
> Just call "auto const auto ref" "auto auto":
>
> auto auto Foo bar( auto auto Foo arg ) {
>     return arg;
> }
>
> =P
>

Even better, with return type inference:

auto auto auto bar( T )( auto auto T arg ) {
     return arg;
}

:p
-- 
Simen