As far as I know, it’s a matter of convenience more than anything. Chances are that you will be using the CI super object a lot in your libraries so why not assign it to a variable to make it a little easier to work with? There are a few other things to consider… If … Read more
This is a singleton because static storage duration for a function local means that only one instance of that local exists in the program. Under the hood, this can very roughly be considered to be equivalent to the following C++98 (and might even be implemented vaguely like this by a compiler): static bool __guard = … Read more
I would say you’re doing it right. Apart of that, some advices for your utility class: Make sure it doesn’t have any state. This is, there’s no field in the class unless it’s declared static final. Also, make sure this field is immutable as well e.g. Strings. Make sure it cannot be a super class … Read more
If I’m not wrong, you can cancel the closing event of that window and instead set visibility to hidden private void Window_Closing(object sender, System.ComponentModel.CancelEventArgs e) { e.Cancel = true; this.Visibility = Visibility.Hidden; }
Setting aside the argument of whether or not implementing the singleton pattern is a good idea, here’s a possible implementation: package singleton type single struct { O interface{}; } var instantiated *single = nil func New() *single { if instantiated == nil { instantiated = new(single); } return instantiated; } single and instantiated are private, … Read more
You can simply use a property observer for the variable, labelChange, and call the function that you want to call inside didSet (or willSet if you want to call it before it has been set): class SharingManager { var labelChange: String = Model().callElements() { didSet { updateLabel() } } static let sharedInstance = SharingManager() } … Read more
Actually, in C++ preferred way is local static object. Printer & thePrinter() { static Printer printer; return printer; } This is technically a singleton though, this function can even be a static method of a class. So it guaranties to be constructed before used unlike with global static objects, that can be created in any … Read more
Remove db.close(); If you try another operation after closing the database, it will give you that exception. The documentation says: Releases a reference to the object, closing the object… Also, check out Android SQLite closed exception about a comment from an Android Framework engineer which states that it is not necessary to close the database … Read more
In defense of singletons: They are not as bad as globals because globals have no standard-enforced initialization order, and you could easily see nondeterministic bugs due to naive or unexpected dependency orders. Singletons (assuming they’re allocated on the heap) are created after all globals, and in a very predictable place in the code. They’re very … Read more
C++11 removes the need for manual locking. Concurrent execution shall wait if a static local variable is already being initialized. ยง6.7 [stmt.dcl] p4 If control enters the declaration concurrently while the variable is being initialized, the concurrent execution shall wait for completion of the initialization. As such, simple have a static function like this: static … Read more