raise

I am trying ot raise a MouseLeftButtonDownEvent by bubbling it up the Visual tree with the following code. MouseButtonEventArgs args = new MouseButtonEventArgs(Mouse.PrimaryDevice,0, MouseButton.Left); args.RoutedEvent = UIElement.MouseLeftButtonDownEvent; args.Source = this; RaiseEvent(args); For some reason the higher level components are not receiving this bubbled event. Am I overlooking something or is it not possible to raise this Mouse event Your problem is that you are raising an event that does not bubble. MouseLeftButtonDownEvent is defined as RoutingStrategy.Direct , which means it

I am wanting to test a function on one of my models that throws specific errors. The function looks something like this: def merge(release_to_delete) raise "Can't merge a release with itself!" if( self.id == release_to_delete.id ) raise "Can only merge releases by the same artist" if( self.artist != release_to_delete.artist ) #actual merge code here end Now I want to do an assert that when I call this function with a parameter that causes each of those exceptions, that the exceptions actually get thrown. I was looking at ActiveSupport documentation, but I wasn't finding anything promising. Any

Following is my code: test = 'abc' if True: raise test + 'def' And when i run this, it gives me the TypeError TypeError: exceptions must be old-style classes or derived from BaseException, not str So what kind of type should the test be? The sole argument to raise indicates the exception to be raised. This must be either an exception instance or an exception class (a class that derives from Exception). Try this: test = 'abc' if True: raise Exception(test + 'def') You can't raise a str . Only Exception s can be raise d. So, you're better off constructing an exception with that string and

I know that if I want to re-raise an exception, I simple use raise without arguments in the respective except block. But given a nested expression like try: something() except SomeError as e: try: plan_B() except AlsoFailsError: raise e # I'd like to raise the SomeError as if plan_B() # didn't raise the AlsoFailsError how can I re-raise the SomeError without breaking the stack trace? raise alone would in this case re-raise the more recent AlsoFailsError . Or how could I refactor my code to avoid this issue? You can store the exception type, value, and traceback in local variables and use the

When I raise my owns exceptions in my Python libraries, the exception stack shows the raise-line itself as the last item of the stack. This is obviously not an error, is conceptually right, but points the focus on something that is not useful for debugging when you're are using code externally, for example as a module. Is there a way to avoid this and force Python to show the previous-to-last stack item as the last one, like the standard Python libraries. Due warning: modifying the behaviour of the interpreter is generally frowned upon. And in any case, seeing exactly where an error was raised

This question already has an answer here: Manually raising (throwing) an exception in Python 7 answers I have read the official definition of "raise", but I still don't quite understand what it does. In simplest terms, what is "raise"? Example usage would help. Ignacio Vazquez-Abrams It has 2 purposes. yentup has given the first one. It's used for raising your own errors. if something: raise Exception('My error!') The second is to reraise the current exception in an exception handler, so that it can be handled further up the call stack. try: generate_exception() except SomeException as e: if