[Boost-users] Using boost.signals with boost.bind

13 Oct 2008

      Hi,

I have one problem with boost.bind and boost.signals I can't understand.
Source code is the best description, therefore

#include <iostream>
#include <boost/signals.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/bind.hpp>

class Func : public boost::noncopyable
{
public:
    void operator()(int i)
    {
        std::cout<<"Func::operator("<< i <<")\n";
    }
};

typedef boost::signal<void ()> signal_type;
Func f;
signal_type::slot_type binded_func = boost::bind<void>(boost::ref(f),42);

int main()
{
    boost::shared_ptr<signal_type> apSig(new signal_type());
    apSig->connect(binded_func);
    (*apSig)();

    apSig.reset(new signal_type());
    boost::signals::connection con = apSig->connect(binded_func);
    std::cout<<"Connected: "<<con.connected()<<" Blocked:
"<<con.blocked()<<"\n";
}

Program output:

Func::operator(42)
Connected: 0 Blocked: 1

Ie, if i create new signal and then try to connect to the same slot, it
fails. If I use not boost::bind object but only boost::function as slot, all
works ok. I can not understand, why?
I used Boost 1.34.1, gcc 4.1.2

Regards,
Sergey Kishchenko