Re: [boost] [MPL] Making Generators

From: David A. Greene (greened_at_[hidden])
Date: 2002-12-07 10:26:16

Aleksey Gurtovoy wrote:

> That's because the MPL's lambda works only with metafunctions which template
> parameters are _types_, and only types:

That's what I suspected.

> 3) a metafunction with template template parameter, can't be used in lambda
> expressions:

Again, what I suspected.

> It _is_ possible to implement a single template along the lines of the
> SHAZAM template you've mentioned early in the thread:
> 
>     template<typename T, typename U, typename V>
>     struct my_type { ... }  // Note: no ::type member
> 
>     typedef SHAZAM<my_type<int, _1, _2> > generator;
> 
>     typedef generator::template apply<char, float>::type my_type_inst;
> 
> but not at the user side - the library internal mechanisms needs to be made
> aware of it. I considered this before, - as well as the option of directly
> supporting the "reduced" metafunction form, - and the latter is currently my
> preference. Will see if something changes after I actually implement it (for
> one, it might slow down the lambda significantly, - but we'll see).

Thanks for considering this.  I think it will be quite useful.  I look
forward to seeing what you come up with!

                             -Dave

-- 
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