"Fernando Cacciola" <fernando_cacciola@hotmail.com> wrote
Say I have a few arbitraty function objects:
A a ; B b ; C c ;
I can easily pipe them toghether using Boost.Bind:
bind(a, bind(b, bind(c,_1) ) )(some_starting_value);
But how do I create such a composed functor programatically from an aribtrary tuple of function objects, as in tuple<A,B,C>?
The idea is to present to the user a simple interface were he pass just a tuple of functors and I do the magic of turning them into a pipe.
I think you may need Fusion to do this... The pseudocode would be roughly something like: unspecified compose(Tuple t, F f) { return compose(tail(t), bind(head(t), f)), } F compose(EmptyTuple, F f) { return f; } compose(tuple(a, b, c), _1) (except I think the order may be inverted) But I don't think current boost::tuple allows for extracting head and tail. Fusion may also have some kind of "fold" algorithm to do this, but I am not sure. Also, if you can't use typeof, you would have to get into bind's implementation details to calculate the return type. FWIW. Regards, Arkadiy