Re: [boost] [result_of] WORKAROUND for problems on MSVC

From: Eric Niebler (eric_at_[hidden])
Date: 2006-10-30 23:24:28

Eric Niebler wrote:
> Eric Niebler wrote:
>> Richard Crossley wrote:
>>  >
>>  > http://article.gmane.org/gmane.comp.lib.boost.user/14256
>>  >
>>  > I ended up giving up with result_of assuming I must be misunderstanding
>>  > something as I never got any response.
>>  >
>>
>> It appears to be the same issue. I added your much simpler test case to 
>> the bug report. Thanks. Sadly, giving up on result_of is not really an 
>> option -- it's standard, now. I hope we can find a work-around.
> 
> 
> Ah-ha! I've found a work-around for this problem. If you have code like 
> this:
> 
> template<typename T>
> struct Foo
> {
>    template<typename Sig> struct result;
>    template<typename This, typename A>
>    struct result<This(A)>
>    {
>      typedef A type;
>    };
>    ...
> }

<snip>

Another work-around is to add the following:

#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1400))
namespace boost
{
   template<typename T>
   struct result_of;

   template<typename T, typename A>
   struct result_of<Foo<T>(A)>
     : Foo<T>::template result<void(A)>
   {};
}
#endif

This works without forcing you to add a bogus base class, which is handy 
if you want Foo<T> to be POD.

-- 
Eric Niebler
Boost Consulting
www.boost-consulting.com