tuple parameter fwd

[kdmult]

On Tuesday, 6 August 2013 at 05:07:51 UTC, Ali Çehreli wrote:
> On 08/05/2013 09:51 PM, kdmult wrote:
>> On Monday, 5 August 2013 at 18:45:49 UTC, kdmult wrote:
>>> class A(P...) {}
>>>
>>> class B(R = A!P, P...) {}
>>>
>>> P... should be rightmost, so how can I use it in the 
>>> preceding parameter?
>>
>> The default parameter value doesn't make sense as it's shown 
>> above.
>> Actually I want to port C++ code which looks like below.
>>
>> template <typename P1>
>> class A1 {};
>> template <typename P1, typename R=A1<P1> >
>> class B1 {}
>>
>> template <typename P1, typename P2>
>> class A2 {};
>> template <typename P1, typename P2, typename R=A2<P1,P2> >
>> class B2 {}
>>
>> and so on.
>>
>> I would use the variadic template parameters. However, I have 
>> no idea
>> how it can be done. Please advise.
>>
>> Thanks.
>
> Direct translation seems to work:
>
> class A1(P1) {}
> class B1(P1, R = A1!P1) {}
>
> class A2(P1, P2) {}
> class B2(P1, P2, R = A2!(P1, P2)) {}
>
> void main()
> {
>     auto a1 = new A1!int;
>     auto b1d = new B1!int;
>     auto b1 = new B1!(int, A1!double);
>     auto a2 = new A2!(int, double);
>     auto b2d = new B2!(int, double);
>     auto b2 = new B2!(int, double, A2!(char, short));
> }
>
> Ali

Is there a way to use variadic template/class parameter instead
of P1, P2, ..., PN ? If it is I could create 2 templated classes
instead of all that copy/pasted classes with P1, P2, etc
parameters.

Thanks.