Paul Davis schrieb:
> On Wed, 2006-10-11 at 21:19 +0300, Paul Pogonyshev wrote:
>> Right, I know this. I wondered if I could not store connection objects,
>> as I know what handlers _this_ object has connected to a signal. I wished
>> to remove them just by (object + function) pair.
>>
>> Here is situation I have. Object A has a pointer to some model, B. It
>> connects to some signals in B to listen for some events. Now, if the
>> model changes to C, A has to disconnect its handlers from B and connect
>> them to C instead. I wondered if I could do that without storing
>> connections, as that seems excessive.
>
> the not very clearly named sigc::trackable::notify_callbacks() gets
> close to this, but is intended to be called from the destructor of a
> trackable or derived type. it will cause all connections to the signals
> of the object it is called for to be dropped. sigc++ keeps track of the
> connections, you see. but note: i do mean *all* connections. you have no
> control over which ones.
What if you use a trackable special for this purpose, bound and hidden?
<code>
#include <iostream>
#include <sigc++/sigc++.h>
void func1()
{
std::cout << "func1" << std::endl;
}
void func2()
{
std::cout << "func2" << std::endl;
}
int _tmain(int argc, _TCHAR* argv[])
{
sigc::signal<void> sig;
sigc::trackable t;
{
sig.connect(sigc::bind(sigc::hide(&func1), sigc::ref(t)));
sig.emit();
t.notify_callbacks();
}
// does nothing
sig.emit();
{
sig.connect(sigc::bind(sigc::hide(&func2), sigc::ref(t)));
sig.emit();
t.notify_callbacks();
}
// does nothing
sig.emit();
std::cin.get();
return 0;
}
</code>
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