Re: [boost] typelists: MPL tutorial + partial review

From: Peter Dimov (pdimov_at_[hidden])
Date: 2001-12-13 16:47:43

From: "David Abrahams" <david.abrahams_at_[hidden]>
> > I'm still not clear on what a "quoted"
> > function object is.
>
> I think you should forget that term, but what Mat means (and it's Mat's
> term, borrowed from lisp) is a class written this way:
>
> struct my_metafunction
> {
>     template <class Param1, ...class ParamN>
>     struct apply
>     {
>         ... // optional metacomputations here
>         typedef type-expression type; // return value
>     };
> };
>
> A uniform interface to metafunctions makes it possible to re-use them in
> different contexts. That's the metafunction formulation used in MPL.

Was this concept only introduced for portability reasons (BTW did you know
that VC 7 supports template template parameters) or there is a deeper
meaning? (I can see one difference right away but I'm interested in the
design rationale.)

--
Peter Dimov
Multi Media Ltd.