Re: [boost] [MPL] Making Generators

From: David Abrahams (dave_at_[hidden])
Date: 2002-12-17 08:11:38

Aleksey Gurtovoy <agurtovoy_at_[hidden]> writes:

> Aleksey Gurtovoy wrote:
>> David A. Greene wrote:
>> > Thanks for considering this.  I think it will be quite 
>> > useful.  I look forward to seeing what you come up with!
>> 
>> Well, it turned out to be a little bit more complicated than 
>> I had foreseen, so it's not there yet. Please stay tuned!
>
> Okay, from this moment MPL's lambda supports "reduced" metafunction form
> directly (if detected):
>
>     template< typename T > struct her
>     {
>         // no 'type' member!
>     };
>
>     typedef lambda< her<_> >::type f;
>     typedef apply<f,int>::type t;
>
>     BOOST_MPL_ASSERT_IS_SAME(t, her<int>);
>
> The "ordinary" metafunctions work as before.

Ah!

That answers my question...

So if I want to generate a template instantiation that /happens/ to
have a nested type (that's not identity), I can't use the reduced
form.

Interesting.  You have to be a little bit careful with that reduced
form then.

-- 
                       David Abrahams
   dave_at_[hidden] * http://www.boost-consulting.com
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