can't use variadic template arg in dependent type

[Larry Evans]

On 01/09/2007 03:15 AM, Daniel Keep wrote:
> Larry Evans wrote:
[snip]
> Ok, it took me a while, but I think I see what you're trying to do here. 
>  Have you tried something along these lines:
> 
>  > class A(Targs...)
>  > {
>  >     private static alias Targs _Targs;
>  > }
>  >
>  > void funA(Ttype)(in Ttype a)
>  > {
>  >     alias Ttype._Targs Targs;
>  > }
> 
> If you really want to make sure that it's an A!(Targs), you could try this:
> 
>  > static if( !is( A!(Targs) == Ttype ) )
>  >     static assert(false, "I can see through your clever deception!");
[snip]
> Hope this helps,

Yes.  It helps.  However, the reason I want'ed to do this
was to try and emulate the "trick" of using c++'s function
template overload resolution rules to determine if a type
was a member of an set of types, like boost's mpl::set.
However, even with your suggestion, I'm still unable to
do it.  So far, what I've got is shown in the 1st attachemnt.
The 2nd attachment shows the compiler error.

This c++ "trick" was described on section 9.10 of the book
described here:

http://www.boost-consulting.com/metaprogramming-book.html

and the cloest c++ counterpart to what I'm trying to do
was posted in another message to this newsgroup:

http://www.digitalmars.com/webnews/newsgroups.php?art_group=digitalmars.D&article_id=46428

The ultimate goal is to use a similar technique to
store the grammar productions to emulate spirit.


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