[Boost-users] Re: using boost::shared_ptr with boost::signal

From: Edward Diener (eddielee_at_[hidden])
Date: 2004-07-24 15:22:14

Oliver Kowalke 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.

What's wrong with:

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

When you now trigger rsig, a.operator()(int, std::string &s) is called.
When you now trigger lsig, a.operator()(std::string &s,0) is called.

What do you mean that "changes of 'a' are never know by the
other signal instance" ?