/// <summary>
/// Inspects the listenerObject for methods decorated with the [ListenTo] attribute.
/// Then, Creates a delegate for each of those methods and binds it to the corresponding
/// Signal instance registered with the SignalContext.
/// Objects that autobind their listeners this way must call UnbindSignals()
/// before they are destroyed.
/// </summary>
protected void BindSignals(System.Object listenerObject)
{
// Try to retrieve MethodInfo's for the targetObject from a cache first, cuz reflection is slow
IEnumerable <MethodInfo> methodInfos = null;
Type listenerObjectType = listenerObject.GetType();
if (this.methodInfoCache.TryGetValue(listenerObjectType, out methodInfos) == false)
{
// If you REEAALLLLY have to, use reflection to look up the methodInfos and cache them
methodInfos = listenerObjectType.GetMethods(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.DeclaredOnly);
this.methodInfoCache[listenerObjectType] = methodInfos;
}
// Loop though all the methodInfos on the targetObject...
foreach (MethodInfo methodInfo in methodInfos)
{
// Identify listener methods by retrieving a SignalListenerAttribute associated with the methodInfo
ListenTo[] listenerBindings = null;
listenerBindings = (ListenTo[])methodInfo.GetCustomAttributes(typeof(ListenTo), false);
// Should be only one ListenToAttribute since they are exclusive (if there is one at all)
foreach (ListenTo listenTo in listenerBindings)
{
// Debug.Log("ListenToAttribute:" + listenTo.SignalType);
// Get an ISignal reference from the signalContext based on the SignalType
ISignal signal = this.SignalContext.GetSignal(listenTo.SignalType);
if (signal != null)
{
var methodParameterCount = methodInfo.GetParameters().Length;
if (methodParameterCount != signal.ParameterCount)
{
throw new ArgumentException($"Incorrect number of parameters found when binding [ListenTo(typeof({ signal.GetType().Name })]. Expected to find {signal.ParameterCount} parameter(s) but found { methodParameterCount }.");
}
Delegate d = null;
try
{
// Create a callback listener for this methodInfo
d = Delegate.CreateDelegate(signal.GetListenerType(), listenerObject, methodInfo);
}
catch (ArgumentException)
{
var parameters = methodInfo.GetParameters();
var parameterTypes = new Type [parameters.Length];
for (int i = 0; i < parameters.Length; i++)
{
parameterTypes[i] = parameters[i].ParameterType;
}
var typeMissmatchMessage = string.Empty;
var parameterIndex = 0;
if (signal.TryGetParameterErrorMessage(parameterTypes, out typeMissmatchMessage, out parameterIndex))
{
throw new ArgumentException($"Incorrect parameter type while binding listener method `{ methodInfo.DeclaringType.Name }.{ methodInfo.Name }`. { typeMissmatchMessage } The { ToOrdinal(parameterIndex+1) } parameter in the listener method does not match what is defined by the Signal.");
}
else
{
throw;
}
}
signal.AddListener(d, listenTo.ListenerType);
// Add the signal listener to the internal list of delegates associated with the listenerObject
// ( so we can easily unbind all the signal listeners later. )
List <SignalListener> delegateList = null;
if (this.signalListenersByObject.TryGetValue(listenerObject, out delegateList) == false)
{
//Debug.Log("adding signal listener:" + methodInfo.Name + " for " + listenerObjectType);
delegateList = new List <SignalListener>();
this.signalListenersByObject[listenerObject] = delegateList;
}
delegateList.Add(new SignalListener(signal, d));
}
else
{
throw new InvalidOperationException($"Unable to Bind Singals for an instance of '{ listenerObjectType }'. The Signal '{ listenTo.SignalType }' is not registered with the SignalManager.");
}
}
}
}