Catch exception in NSArrayController
I have a classical binding usecase: A NSArrayController is used for
displaying the columns of a NSTableView. The columns itself therefore
use the arrangedObject method of the NSArrayController. In the get
methods of the model itself (which normally return an NSString* which
should be displayed in the column), there could occur an exception. I
want to catch that exception in the NSArrayController. I therefore
subclassed the NSArrayController and overwrote valueForKeyPath with a
simple:
- (id)valueForKeyPath:(NSString *)keyPath {
try {
[super valueForKeyPath:keyPath];
}
catch (...) {
// want to get here, if there is an exception thrown within the
model class
}
}
Unfortunately it is only called with arrangedObjects. At that point no
exception is thrown yet. Somewhere after that a valueForKeyPath must
be executed on that returned arrangedObjects. Since I have not
subclassed this proxy class, I cannot intercept its valueForKeyPath
method and therefore cannot catch the exception. Is there a simple way
to catch exceptions in the controller class which is thrown during
calling a get method (over binding mechanims)?
Thanks for any help.
Konrad
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Re: Catch exception in NSArrayController
On 9/17/09 1:26 PM, Konrad Windszus said:
I have a classical binding usecase: A NSArrayController is used for
displaying the columns of a NSTableView. The columns itself therefore
use the arrangedObject method of the NSArrayController. In the get
methods of the model itself (which normally return an NSString* which
should be displayed in the column), there could occur an exception. I
want to catch that exception in the NSArrayController. I therefore
subclassed the NSArrayController and overwrote valueForKeyPath with a
simple:
- (id)valueForKeyPath:(NSString *)keyPath {
try {
[super valueForKeyPath:keyPath];
}
catch (...) {
// want to get here, if there is an exception thrown within the
model class
}
}
Unfortunately it is only called with arrangedObjects. At that point no
exception is thrown yet. Somewhere after that a valueForKeyPath must
be executed on that returned arrangedObjects. Since I have not
subclassed this proxy class, I cannot intercept its valueForKeyPath
method and therefore cannot catch the exception. Is there a simple way
to catch exceptions in the controller class which is thrown during
calling a get method (over binding mechanims)?
What's this exception you speak of? Are you throwing or is the system?
--
Sean McBride, B. Eng s...@rogue-research.com
Rogue Researchwww.rogue-research.com
Mac Software Developer Montréal, Québec, Canada
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Re: Catch exception in NSArrayController
Exceptions are used for programmer error in Cocoa. They are not a general error signaling mechanism. There are a few unfortunate exceptions, though: Distributed Objects and Objective-C++. If you are not using these technologies, you should not be throwing or catching exceptions as a control-flow technique. Cocoa isn't, generally speaking, exception-safe. --Kyle Sluder ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Catch exception in NSArrayController
I am throwing it myself (or more exactly a c++ library I call within a
get method of the model class). But I don't want to handle the
exception in the model class, but rather in the controller, which can
then disable some UI buttons.
Am 17.09.2009 um 16:41 schrieb Sean McBride:
On 9/17/09 1:26 PM, Konrad Windszus said:
I have a classical binding usecase: A NSArrayController is used for
displaying the columns of a NSTableView. The columns itself therefore
use the arrangedObject method of the NSArrayController. In the get
methods of the model itself (which normally return an NSString* which
should be displayed in the column), there could occur an exception. I
want to catch that exception in the NSArrayController. I therefore
subclassed the NSArrayController and overwrote valueForKeyPath with a
simple:
- (id)valueForKeyPath:(NSString *)keyPath {
try {
[super valueForKeyPath:keyPath];
}
catch (...) {
// want to get here, if there is an exception thrown within the
model class
}
}
Unfortunately it is only called with arrangedObjects. At that point
no
exception is thrown yet. Somewhere after that a valueForKeyPath must
be executed on that returned arrangedObjects. Since I have not
subclassed this proxy class, I cannot intercept its valueForKeyPath
method and therefore cannot catch the exception. Is there a simple
way
to catch exceptions in the controller class which is thrown during
calling a get method (over binding mechanims)?
What's this exception you speak of? Are you throwing or is the
system?
--
Sean McBride, B. Eng s...@rogue-research.com
Rogue Researchwww.rogue-research.com
Mac Software Developer Montréal, Québec, Canada
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Re: Catch exception in NSArrayController
On Sep 17, 2009, at 8:27 AM, Konrad Windszus konra...@gmx.de wrote: I am throwing it myself (or more exactly a c++ library I call within a get method of the model class). But I don't want to handle the exception in the model class, but rather in the controller, which can then disable some UI buttons. This isn't safe. You will need to wrap that class in an Objective-C class that converts the exception into some other means of signifying to the controller layer that it should disable the UI. --Kyle Sluder ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
