JarCastingThis is a Java reinterpretation of Robert Penner's as3-signals. It keeps the simple event declaration and dispatching, while adding a dash of type-safety afforded by Java's generics.
Usage
Using a signal is a 3 step process. First, create a signal on the class that will be firing events:
public class Dispatcher {
/** Dispatches the old value and the new value after it changes. */
public final Signal2<String, String> onChanged = Signals.newSignal2();
}
Then, add listeners to that signal as appropriate:
public class InterestedParty {
public void connectToDispatcher (Dispatcher d)
{
d.onChanged.add(new Listener1<String>() {
public void apply (String oldValue) {
System.out.println("Dispatcher changed from " + oldValue);
}});
}
}
or
d.onChanged.add(new Listener0() {
public void apply () {
System.out.println("I'll only be called for one dispatch!");
}
}).once();
if the listener only wants to receive the next dispatch.
Finally, dispatch that signal when the event occurs:
onChanged.dispatch("oldValue", "newValue");
That'll call apply on all the added listeners.
If a listener is no longer interested in a signal, it can be removed from the signal, or Connection.disconnect can be called.
Connecting, disconnecting, and dispatching is thread-safe. After Signal.disconnect(Listener) or Connection.disconnect returns, a listener is guaranteed to never receive another call to its apply method.
Getting
The 0.3 release of signals is available via Maven Central. Just add this to your POM:
<dependency>
<groupId>com.threerings</groupId>
<artifactId>signals</artifactId>
<version>0.3</version>
</dependency>
You can also download it directly from Maven Central.
