Re: [boost] limited form of type deduction

From: Joel de Guzman (joel_at_[hidden])
Date: 2003-10-11 18:17:31

Brian McNamara <lorgon_at_[hidden]> wrote:
> On Sat, Oct 11, 2003 at 08:37:24PM +0300, Peter Dimov wrote:
>> Joel de Guzman wrote:
>> 
>>>         typedef result_of_plus<int, double>::type result;
>> 
>> You should name that
>> 
>>     typedef result_of<plus(int, double)>::type result;
>> 
>> instead. :-)
> 
> There is a smiley, but seriously, if you did
> 
>    struct op_plus {
>       template <class R> struct result;
>       template <class F, class A1, class A2> struct result<F(A1,A2)> {
>          typedef typename result_of_plus<A1,A2>::type type;
>       };
>    };
>    // etc.
> 
> then
> 
>    typedef result_of< op_plus(int, double) >::type result;
> 
> would truly work.  (Names like op_plus are just used as tags which stand
> for the corresponding C++ operators.)

This is exactly how I envision it to be used. The result_of_plus is just a
low-level utility.

-- 
Joel de Guzman
http://www.boost-consulting.com
http://spirit.sf.net