constraints,template specialization,drop IFTI

[BLS]

Daniel Keep wrote:
> 
> BLS wrote:
>> I have somehow the idea that D constraints and template specialization
>> should merge.
>> Guess what I want to say is that instead of accepting the  compiler
>> decision for template specialization  a constraints could be used for :
>> "I am not the one who is able to fulfill your needs.. try this template
>> instead."
>>
>> template Foo(int N)
>>         if ( ( N & 1 _else_ FooOdd!(int N)) )
>> {
>>     ...
>> }
> 
> Firstly, why not
> 
> template Foo(int N)
>     if( N&1 ) else FooOdd!N
> {
>     ...
> }
> 
> Secondly, why?  I mean, isn't this equivalent to:
> 
> template Foo(int N)
> {
>     static if( N&1 ) { ... }
>     else alias FooOdd!N Foo;
> }
> 
>> ...
>>
>> A smarter implementation will probably support tuple based pattern
>> matching.
> 
> Huh?  Isn't this how template matching works anyway; match a given
> argument tuple against the available templates?

sure, but Mister Compiler makes that decision, What I want is _also_ 
programmer control.

template Foo(T : Tuple)
	match T { case... }
{
//default
}


> 
> Lastly, what's that in the subject about dropping IFTI?  I seriously
> hope you're joking about that.

ok, wrong description, wrong words. should be ->  make implicit function 
template instantiation explicit :) work.