Oliver Kowalke <oliver.kowalke@t-online.de> wrote:

Hi,

I want to use boost::shared_ptr with boost::signal.

class A { private:         int     _i; public:         A() : _i( 0) {}

        void operator()( int, std::string & s)         { i+= 1; }

        void operator()( std::string & s, int)         { i+= 2; } };

boost::shared_ptr< A > a( new A() ); boost::signal< void( int, std::string &) > rsig; boost::singal< void( std::string &, int) > lsig;

rsig.connect( a); lsig.connect( a);

rsig(0,"called from right side"); lsig("called from left side",0);

Because a is a smart_ptr this code would not compile because operator() is not a member function. If I dereference the smart pointer when I connect to signal, changes of a are never know by the other signal instance. Maybe I can use a proxy class which aggregates the smart pointer but maybe there is a better solution?!

As a general rule, functors are expected to be copiable and not to have mutable state of their own. So how about putting the shared_ptr inside A instead: class A { private:      boost::shared_ptr<int> _i; public:      A() : _i(new int(0)) {}     void operator()(int, std::string & s)      { *_i += 1; }    void operator()(std::string & s, int)      { *_i += 2; } }; A a;