Add BMessenger::SetTo() to reinitialize a BMessenger.

This allows to reuse BMessenger objects for different targets, or to
recheck validity after initial creation. With that one can use the same
BMessenger after launching an application that was previously not found
valid for example.

headers/os/app/Messenger.h

@@ -48,6 +48,9 @@ public:
 	
 	// Operators and misc
 
+	status_t SetTo(const char *signature, team_id team = -1);
+	status_t SetTo(const BHandler *handler, const BLooper *looper = NULL);
+
 	BMessenger &operator=(const BMessenger &from);
 	bool operator==(const BMessenger &other) const;
 
@@ -63,6 +66,8 @@ private:
 
 	void _SetTo(team_id team, port_id port, int32 token);
 	void _InitData(const char *signature, team_id team, status_t *result);
+	void _InitData(const BHandler *handler, const BLooper *looper,
+		status_t *result);
 
 private:
 	port_id	fPort;

src/kits/app/Messenger.cpp

@@ -98,33 +98,7 @@ BMessenger::BMessenger(const BHandler* handler, const BLooper* looper,
 	fHandlerToken(B_NULL_TOKEN),
 	fTeam(-1)
 {
-	status_t error = (handler || looper ? B_OK : B_BAD_VALUE);
-	if (error == B_OK) {
-		if (handler) {
-			// BHandler is given, check/retrieve the looper.
-			if (looper) {
-				if (handler->Looper() != looper)
-					error = B_MISMATCHED_VALUES;
-			} else {
-				looper = handler->Looper();
-				if (looper == NULL)
-					error = B_MISMATCHED_VALUES;
-			}
-		}
-		// set port, token,...
-		if (error == B_OK) {
-			AutoLocker<BLooperList> locker(gLooperList);
-			if (locker.IsLocked() && gLooperList.IsLooperValid(looper)) {
-				fPort = looper->fMsgPort;
-				fHandlerToken = (handler
-					? _get_object_token_(handler) : B_PREFERRED_TOKEN);
-				fTeam = looper->Team();
-			} else
-				error = B_BAD_VALUE;
-		}
-	}
-	if (_result)
-		*_result = error;
+	_InitData(handler, looper, _result);
 }
 
 
@@ -427,6 +401,50 @@ BMessenger::SendMessage(BMessage *message, BMessage *reply,
 //	#pragma mark - Operators and misc
 
 
+/*!	\brief Reinitializes a BMessenger to target the already running application
+	identified by the supplied signature and/or team ID.
+
+	When only a signature is given, and multiple instances of the application
+	are running it is undeterminate which one is chosen as the target. In case
+	only a team ID is passed, the target application is identified uniquely.
+	If both are supplied, the application identified by the team ID must have
+	a matching signature, otherwise the initilization fails.
+
+	\param signature The target application's signature. May be \c NULL.
+	\param team The target application's team ID. May be < 0.
+	\return The result of the reinitialization.
+*/
+status_t
+BMessenger::SetTo(const char *signature, team_id team)
+{
+	status_t result = B_OK;
+	_InitData(signature, team, &result);
+	return result;
+}
+
+
+/*!	\brief Reinitializes a BMessenger to target the local BHandler and/or
+	BLooper.
+
+	When a \c NULL handler is supplied, the preferred handler in the given
+	looper is targeted. If no looper is supplied the looper the given handler
+	belongs to is used -- that means in particular, that the handler must
+	already belong to a looper. If both are supplied the handler must actually
+	belong to looper.
+
+	\param handler The target handler. May be \c NULL.
+	\param looper The target looper. May be \c NULL.
+	\return The result of the reinitialization.
+*/
+status_t
+BMessenger::SetTo(const BHandler* handler, const BLooper* looper)
+{
+	status_t result = B_OK;
+	_InitData(handler, looper, &result);
+	return result;
+}
+
+
 /*!	\brief Makes this BMessenger a copy of the supplied one.
 
 	\param from the messenger to be copied.
@@ -564,6 +582,54 @@ BMessenger::_InitData(const char* signature, team_id team, status_t* _result)
 }
 
 
+/*!	\brief Initializes the BMessenger to target the local BHandler and/or
+	BLooper.
+
+	When a \c NULL handler is supplied, the preferred handler in the given
+	looper is targeted. If no looper is supplied the looper the given handler
+	belongs to is used -- that means in particular, that the handler must
+	already belong to a looper. If both are supplied the handler must actually
+	belong to looper.
+
+	\param handler The target handler. May be \c NULL.
+	\param looper The target looper. May be \c NULL.
+	\param result An optional pointer to a pre-allocated status_t into which
+		   the result of the initialization is written.
+*/
+void
+BMessenger::_InitData(const BHandler* handler, const BLooper* looper,
+	status_t* _result)
+{
+	status_t error = (handler || looper ? B_OK : B_BAD_VALUE);
+	if (error == B_OK) {
+		if (handler) {
+			// BHandler is given, check/retrieve the looper.
+			if (looper) {
+				if (handler->Looper() != looper)
+					error = B_MISMATCHED_VALUES;
+			} else {
+				looper = handler->Looper();
+				if (looper == NULL)
+					error = B_MISMATCHED_VALUES;
+			}
+		}
+		// set port, token,...
+		if (error == B_OK) {
+			AutoLocker<BLooperList> locker(gLooperList);
+			if (locker.IsLocked() && gLooperList.IsLooperValid(looper)) {
+				fPort = looper->fMsgPort;
+				fHandlerToken = (handler
+					? _get_object_token_(handler) : B_PREFERRED_TOKEN);
+				fTeam = looper->Team();
+			} else
+				error = B_BAD_VALUE;
+		}
+	}
+	if (_result)
+		*_result = error;
+}
+
+
 /*!	\brief Returns whether the first one of two BMessengers is less than the
 	second one.