When you want to “copy”/Expose the base class’ API, you use inheritance. When you only want to “copy” functionality, use delegation. One example of this: You want to create a Stack out of a List. Stack only has pop, push and peek. You shouldn’t use inheritance given that you don’t want push_back, push_front, removeAt, et … Read more
Preface: POP and OOP are not mutually exclusive. They’re design paradigms that are greatly related. The primary aspect of POP over OOP is that is prefers composition over inheritance. There are several benefits to this. In large inheritance hierarchies, the ancestor classes tend to contain most of the (generalized) functionality, with the leaf subclasses making … Read more
I’ve actually been doing something like this recently but am using spring security kerberos. I put an example on github here. The key thing that I found that I needed set up to use constrained delegation like you want it and S4U2Proxy was to make sure (if you’re using Oracle/OpenJDK) you set isInitiator=true in your … Read more
Delegates send messages to you. For example: if you use the accelerometer delegate, you will get messages about the accelerometer. If you use that new neutrino-detection delegate, you will get messages about any neutrinos detected in the area. If you use PopUps, PopUps send you messages. And the way that is done, is with the … Read more
The crucial distinction between Python’s __init__ and those other languages constructors is that __init__ is not a constructor: it’s an initializer (the actual constructor (if any, but, see later;-) is __new__ and works completely differently again). While constructing all superclasses (and, no doubt, doing so “before” you continue constructing downwards) is obviously part of saying … Read more
You have an incredible number of choices to achieve delegates in C++. Here are the ones that came to my mind. Option 1 : functors: A function object may be created by implementing operator() struct Functor { // Normal class/struct members int operator()(double d) // Arbitrary return types and parameter list { return (int) d … Read more
What is Delegation? First of all, you should know that Delegation Pattern is not exclusive for iOS world: In software engineering, the delegation pattern is a design pattern in object-oriented programming that allows object composition to achieve the same code reuse as inheritance. But working with delegation in the iOS world is so common, I … Read more
Here’s a little help on delegates between two view controllers: Step 1: Make a protocol in the UIViewController that you will be removing/will be sending the data. protocol FooTwoViewControllerDelegate:class { func myVCDidFinish(_ controller: FooTwoViewController, text: String) } Step2: Declare the delegate in the sending class (i.e. UIViewcontroller) class FooTwoViewController: UIViewController { weak var delegate: FooTwoViewControllerDelegate? … Read more