[boost] Can I get the function signature of the result of a bind() ?

21 Nov 2004

      Sorry if my question seems somehow weird. I already posted a similar one
to the users list but with no result. So I try again but also post a small
example to make my question clear.

The purpose of the example is to autoconnect a couple of member classes
to a containing class without the need to explicitely call the constructors
of the member classes:

#include <boost/signal.hpp>
#include <boost/any.hpp>
#include <boost/bind.hpp>

boost::any pinit; // todo: should be thread local in MT version

template<typename Function>
struct ctor_signal_push : public boost::signal<Function>{
    ctor_signal_push() {    pinit = this; } // todo: make it a stack
};

template<typename Signature, typename Function>
void ctor_connect(Function fn)
{
    boost::any_cast<ctor_signal_push<Signature>* >(pinit)->connect(fn);
    // can this be done without the Signature parameter?
    // i.e. can the Signature be deduced from Function? (which might be 
a functor)
}

class A;

class B {
public:
    B() { ctor_connect<void (A*)>(boost::bind(init, this, _1));    }
    void init(A* p) { pOuter = p; };
    A* pOuter;
};

class C {
public:
    C() { ctor_connect<void (A*)>(boost::bind(init, this, _1));    }
    void init(A* p) { pOuter = p; };
    A* pOuter;
};

class A {
public:
    A();
    ctor_signal_push<void (A*)> init;
        B aB;
        C aC;
        B aB1;
        B aB2;
    // ctor_signal_pop;
};

A::A()
{
    init(this); // connect all member classes
}

int main(int argc, char* argv[])
{
    A aA;
    return 0;
}

This does work well so far, but I would like to get rid of the explicit 
"void (A*)"
parameter in
ctor_connect<void (A*)>(boost::bind(init, this, _1));
Is this possible?

Perhaps I am even trying to do something that I should better avoid 
because there is
a better solution available. Does anyone know?

Thank you for any hints,
Roland

[boost] Can I get the function signature of the result of a bind() ?

Roland Schwarz