In this case the compiler detects that s is written but not read, and deliberately suppresses the warning. The reason is because C# is a garbage-collected language, believe it or not. How do you figure that? Well, consider the following. You have a program which calls a method DoIt() that returns a string. You do … Read more
Because ending the generator is not a common event (I know it will always happen, but it only happens once). Throwing the exception is considered expensive. If an event is going to succeed 99% of the time and fail 1%, using try/except can be much faster than checking if it’s okay to access that data … Read more
The basic guideline is to use exceptions for something really exceptional**. For an “ordinary” failure, it’s far better to use Option or Either. If you are interfacing with Java where exceptions are thrown when someone sneezes the wrong way, you can use Try to keep yourself safe. Let’s take some examples. Suppose you have a … Read more
Important note The following discussion assumes that we are talking about code structured as in the example above: no matter which alternative is chosen, an exception will cause the method to logically stop doing whatever it was in the middle of. As long as you intend to do the same thing no matter which statement … Read more
If you want, you can add throws clauses to your methods. Then you don’t have to catch checked methods right away. That way, you can catch the exceptions later (perhaps at the same time as other exceptions). The code looks like: public void someMethode() throws SomeCheckedException { // code } Then later you can deal … Read more
You can use a do-while loop instead to eliminate the first input.nextInt(). int students = 0; do { try { // Get input System.out.print(“Enter the number of students: “); students = input.nextInt(); } catch (InputMismatchException e) { System.out.print(“Invalid number of students. “); } input.nextLine(); // clears the buffer } while (students <= 0); // Do … Read more
Declarative event binding is only supported in static HTML in a components template. If you want to subscribe to events of elements dynamically added, you need to do it imperatively. elementRef.nativeElement.querySelector(…).addEventListener(…) or similar. If you want to be WebWorker-safe, you can inject the Renderer constructor(private elementRef:ElementRef, private renderer:Renderer) {} and use instead this.renderer.listen(this.elementRef.nativeElement, ‘click’, (event) … Read more
Catching exceptions is expensive, but exceptions should be exceptional (read, not happen very often). If exceptions are rare, try/catch is faster than LBYL. The following example times a dictionary key lookup using exceptions and LBYL when the key exists and when it doesn’t exist: import timeit s = [] s.append(”’\ try: x = D[‘key’] except … Read more
Since Java 9 you can declare and initialize the variable used inside try-with-resources outside the block. The only additional requirement for variable is that it has to be effectively final. So now it is possible to do: CloseableResource thing = methodThatCreatesAThingAndDoesSomeSideEffect(); try (thing) { // do some interesting things } thing.collectSomeStats(); Hope it helps.