To expand on the answer by bradtgmurray, you may want to make one exception to the pure virtual method list of your interface by adding a virtual destructor. This allows you to pass pointer ownership to another party without exposing the concrete derived class. The destructor doesn’t have to do anything, because the interface doesn’t … Read more
It’s not always necessary, but it does have its uses. Suppose we wanted to make a copy method on the base Person class. Like this: // define the Person Class function Person(name) { this.name = name; } Person.prototype.copy = function() { // return new Person(this.name); // just as bad return new this.constructor(this.name); }; // define … Read more
Modify your constructor to the following so that it calls the base class constructor properly: public class MyExceptionClass : Exception { public MyExceptionClass(string message, string extrainfo) : base(message) { //other stuff here } } Note that a constructor is not something that you can call anytime within a method. That’s the reason you’re getting errors … Read more
They are absolutely different. Inheritance is an “is-a” relationship. Composition is a “has-a”. You do composition by having an instance of another class C as a field of your class, instead of extending C. A good example where composition would’ve been a lot better than inheritance is java.util.Stack, which currently extends java.util.Vector. This is now … Read more
Okay, let’s play a little mind game: From the above image we can see: When we create a function like function Foo() {}, JavaScript creates a Function instance. Every Function instance (the constructor function) has a property prototype which is a pointer. The prototype property of the constructor function points to its prototype object. The … Read more
Use of .apply() with ‘new’ operator. Is this possible?
Actually, there is nothing wrong with public inheritance of std::vector. If you need this, just do that. I would suggest doing that only if it is really necessary. Only if you can’t do what you want with free functions (e.g. should keep some state). The problem is that MyVector is a new entity. It means … Read more
Base class constructors are automatically called for you if they have no argument. If you want to call a superclass constructor with an argument, you must use the subclass’s constructor initialization list. Unlike Java, C++ supports multiple inheritance (for better or worse), so the base class must be referred to by name, rather than “super()”. … Read more
The way to make this work is to iterate over the list and cast the elements. This can be done using ConvertAll: List<A> listOfA = new List<C>().ConvertAll(x => (A)x); You could also use Linq: List<A> listOfA = new List<C>().Cast<A>().ToList();
What’s the difference? SomeBaseClass.__init__(self) means to call SomeBaseClass‘s __init__. while super().__init__() means to call a bound __init__ from the parent class that follows SomeBaseClass‘s child class (the one that defines this method) in the instance’s Method Resolution Order (MRO). If the instance is a subclass of this child class, there may be a different parent … Read more