Fun with templates

[TommiT]

On Sunday, 7 July 2013 at 06:22:17 UTC, Manu wrote:
> On 7 July 2013 16:02, TommiT <tommitissari at hotmail.com> wrote:
>> I think Artur's solution is the cleanest one [..]
>
> Maybe so, but I just have my suspicions that it will never fly, 
> and I think a solution here is actually pretty important.

You think it won't fly because it's a breaking change? I also 
think a solution is needed.

Earlier you said that your suggestion either is implementable or 
it isn't. If you put it that way, the answer must be that it is 
implementable, because if a problem is computable then it is 
possible to write a compiler that can compute it given that 
there's an ambiguous solution to the problem. But since compiler 
writers are only human, I think there might the third possibility 
which is that it's just a too big of an undertaking for a small 
group of humans to write that compiler. For example here's an 
example where the compiler would need to solve the equation:
cast(int) (3.5 ^^ x * x ^^ 4 + 5 * x) == 206
for x. And not only does the compiler need to figure out an 
answer to the problem, it needs to figure out that there aren't 
multiple answers to the problem.

struct Soo(int n) { }

template Too(int x)
{
     alias Too = Soo!(cast(int) (3.5 ^^ x * x ^^ 4 + 5 * x));
}

void foo(int n)(Too!n) { }

void main()
{
     Soo!206 s;
     foo(s); // should call foo!2(s)
}