Re: [boost] result_of?

From: Doug Gregor (dgregor_at_[hidden])
Date: 2004-11-22 19:15:35

On Nov 22, 2004, at 7:05 PM, Brock Peabody wrote:

> I replaced my home grown result_type<> with boost::result_of<> today 
> only to
> find that I couldn't get it to work.  When I try to use result_of with 
> VC
> 7.1:
>
>    struct test_struct {
>
>       typedef int result_type;
>    };
>
>    boost::result_of<test_struct>::type i = 5;
>
> I get:
>
>    test.cpp(10) : error C2027: use of undefined type 
> 'boost::result_of<F>'
>
> I get the same results if I use function types of pointer to function 
> types:
>
>    boost::result_of<int (*)()>::type i = 5;
>    boost::result_of<int ()()>::type i = 5;
>
> Am I missing something?

Yes :)

With result_of, you pass the function object type _and_ the types of 
the arguments, e.g.,

        boost::result_of<test_struct(int, float)>::type

That's how result_of is able to deal with polymorphic function objects.

        Doug