Hello,
I'm using KVO on a Distributed Object, and I am binding my UI controls
based on the observer.
For example:
MonkeyViewController.isEatingABanana -> Binded to a UI checkbox.
MonkeyViewController.m:
@propery (readwrite, assign) BOOL isEatingABanana;
-(id)init {
...
[MonkeyBrainDOObject addObserver:self
forKeyPath:@"banana"
options:(NSKeyValueObservingOptionNew |
NSKeyValueObservingOptionOld)
context:NULL];
...
}
- (void)observeValueForKeyPath:(NSString *)keyPath
ofObject:(id)object
change:(NSDictionary *)change
context:(void *)context
{
if ([keyPath isEqualToString:@"banana]") {
[self willChangeValueForKey:@"isEatingABanana"];
isEatingABanana = [change objectForKey:NSKeyValueChangeNewKey] boolValue];
[self didChangeValueForKey:@"isEatingABanana"];
}
}
- (void)setIsEatingABanana:(BOOL)flag
{
[MonkeyBrainDOObject setBanana:flag];
isEatingABanana = flag;
}
This indeed works, and we save some hassles of sending NSNotifications and such.
So, what I'm wondering is if the following code is sufficient enough
for the IPC exception handling?
Instead of having to manually write @try/@catch wherever I doing some
IPC, I create a wrapper object around the DO to handle the exceptions.
This wrapper class is simply an NSObject, and will call the methods
methodSignatureForSelector, and forwardInvocation when I try to use
MonkeyBrainDOObject methods (since the wrapper does not understand
them). I can then insert a @try/@catch when I forward the invokations
to the actual DO object.
MonkeyBrainWrapper.m : NSObject
- (NSMethodSignature *)methodSignatureForSelector:(SEL)selector
{
return [MonkeyBrainDOObject methodSignatureForSelector:selector];
// maybe I can use extra code to make sure MonkeyBrainDOObject
responds to the selector.
}
- (void)forwardInvocation:(NSInvocation *)invocation
{
@try {
[invocation invokeWithTarget:MonkeyBrainDOObject];
} @catch (NSException *e) {
// Oh no! some went wrong with the IPC. But it's ok, I caught you.. :P
}
}
So, instead of calling directly on the MonkeyBrainDOObject in my
MonkeyViewController, I would now call my MonkeyBrainWrapper object,
which has explicit exception handling rather than the one handle by
the NSApplication.
Should that be enough for exception handling on both ends of the IPC?
Or do I need some explicit exception handling on the other end? It
seems when I tested it out, my other end never threw anything when the
connection broke.
Also, is there maybe a better approach to all of this? My old code had
a bunch of NSNotifications being sent/received whenever something
needed updating on the UI, and I found this approach to be a lot
cleaner.
Edward
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