[Boost-users] result_of example?

From: Fedor Pikus (fpikus_at_[hidden])
Date: 2004-12-13 01:10:55

I was trying to come up with a solution for the following problem:
say, I want to declare this class
template <typename T1, typename T2> class A
{
    public:
    A( T1 x, T2 y ) : xy( x + y ) {}
    private:
    The_Right_Type xy;
};

Or I want to declare a function template:
template <typename T1, typename T2> The_Right_Type f( T1 x, T2 y ) {
return x + y; }

The problem is, of course, what is The_Right_Type?
I could not get a solution better than something which would require
me to "register" all types in some way (then I could get types of all
expressions involving registered types). Then Scott Meyers suggested I
look at boost::result_of.

It looks very cool except I can't figure out how to use it :( I
searched the Boost mailing lists, found some incomplete examples and
some broken tinyurl links, but nothing which would show me how to use
it. Looking at the proposal, I could see how it is used inside a
template where I already have types, but not how to get a type out of
an expression in the first place.

Now the question: can result_of solve the problem above, and would
someone be kind enough to show me an example of how to use it?

Thanks in advance,
Fedor

-- 
Fedor G Pikus (fpikus_at_[hidden])
http://www.pikus.net
http://wild-light.com