C++0x Concepts - Dead?

[aarti_pl]

Walter Bright pisze:
> aarti_pl wrote:
>> My proposal would make meta programing in D much more intuitive 
>> (because of using rules - not bunch of corner cases as it is today). 
>> Unfortunately almost no one from NG commented on that...
> 
> Thank you, but I don't see in your proposal a method that can:
> 
> 1. instantiate templates only if a value argument is prime or odd.
> 
> 2. instantiate templates only on a type which supports addition and has 
> the method foo.
> 
> Note that C++ Concepts could do (2) but could not do (1).

ad.1

template normalizedType((T U N : U[N=size_t]) && (N & 1))

As it is stated in proposal commas are only syntax sugar for more 
general form with '&&'.

ad.2.

This case is in fact the same as 1. Because of the fact that A, B, C <=> 
A && B && C, you can create expressions as you want just using second 
form with logical operators. In this case you should just use proper 
compile time reflection mechanism in D to get information about type 
properties.

BR
Marcin Kuszczak
(aarti_pl)