Hi Marco, On 9/6/07, Marco Costalba <mcostalba@gmail.com> wrote:
If you look at the implementation(s) for the "functor" type in the dispatcher, it would be possible for it to provide the three operator() overloads following signatures given as a fusion::vector<> by containing three boost::function<>'s each having one signature, and having the deduction done during compile-time still. So that means:
d[0](1); // foo() is called d[0](1, 2); // bar() is called d[0](1, 2.1); // foobar() is called
More or less I can achieve this also with my very simple and raw implementation, what I cannot achieve is something like this:
void foobar3(int a, double b, double c) { ... }; void foobar4(int a, double b, std::string) { ... };
d[0] = &foobar3; d[0] = &foobar4;
d[0](1, 1, 1); // foobar3() is called
d[0](1, 2.4, "Test"); // foobar4() is called
Is this possible using fusion::vector<> ?
The intended use of fusion::vector<> is to become a compile-time container (think of mpl::vector<>) of the function prototypes/signatures which the 'functor' wrapper should implement/support. At the same time, a fusion::vector<> can map a numeric index to a runtime instance (ala tuple) of the type defined in the indexed element of the vector. In code, that looks like: fusion::vector<int, double, string> a(1, 2.1, "1"); int i = get<0>(a); // 1 at compile time double d = get<1>(a); // 2.1 at compile time string s = get<2>(a); // "1" at compile time Though I'm pretty sure I'm not doing Boost.Fusion docs justice by my above description, I think it would be better if you checked it out for yourself. ;)
I think Boost.Fusion will definitely help in this extension through the fold<> algorithm/metafunction (for linear inheritance for the signature overloads).
Boost.Fusion is another place where I'm going to look :-) thanks.
I definitely hope you find Boost.Fusion useful as well -- it's already been useful in my work, and I'm thankful there's something like this that has come along. -- Dean Michael C. Berris http://cplusplus-soup.blogspot.com/ mikhailberis AT gmail DOT com +63 928 7291459