Most of the confusion in the question/answers here surrounds the definition of Inheritance. Obviously, as @DigitalRoss explains an OBJECT of a subclass must contain its superclass’s private fields. As he states, having no access to a private member doesn’t mean its not there. However. This is different than the notion of inheritance for a class. … Read more
All methods that are accessible are inherited by subclasses. From the Sun Java Tutorials: A subclass inherits all of the public and protected members of its parent, no matter what package the subclass is in. If the subclass is in the same package as its parent, it also inherits the package-private members of the parent. … Read more
The answer to your question depends on one very important aspect: Are your base classes designed for multiple inheritance? There are 3 different scenarios: The base classes are unrelated, standalone classes. If your base classes are separate entities that are capable of functioning independently and they don’t know each other, they’re not designed for multiple … Read more
There are several ways to model inheritance in a database. Which you choose depends on your needs. Here are a few options: Table-Per-Type (TPT) Each class has its own table. The base class has all the base class elements in it, and each class which derives from it has its own table, with a primary … Read more
I wrote an article about that: Abstract classes and interfaces Summarizing: When we talk about abstract classes we are defining characteristics of an object type; specifying what an object is. When we talk about an interface and define capabilities that we promise to provide, we are talking about establishing a contract about what the object … Read more
Use the super() function: class Foo(Bar): def baz(self, **kwargs): return super().baz(**kwargs) For Python < 3, you must explicitly opt in to using new-style classes and use: class Foo(Bar): def baz(self, arg): return super(Foo, self).baz(arg)
Nope, there is none, unless you do the mapping yourself. C++ has no mechanism to create objects whose types are determined at runtime. You can use a map to do that mapping yourself, though: template<typename T> Base * createInstance() { return new T; } typedef std::map<std::string, Base*(*)()> map_type; map_type map; map[“DerivedA”] = &createInstance<DerivedA>; map[“DerivedB”] = … Read more
Thoughts: Avoid extending JFrame as it ties your GUI to being, well a JFrame. If instead you concentrate on creating JPanels instead, then you have the freedom to use these JPanels anywhere needed — in a JFrame, or JDialog, or JApplet, or inside of another JPanel, or swapped with other JPanels via a CardLayout. Avoid … Read more
The override modifier may be used on virtual methods and must be used on abstract methods. This indicates for the compiler to use the last defined implementation of a method. Even if the method is called on a reference to the base class it will use the implementation overriding it. public class Base { public … Read more
It is because name lookup stops if it finds a name in one of your bases. It won’t look beyond in other bases. The function in B shadows the function in A. You have to re-declare the function of A in the scope of B, so that both functions are visible from within B and … Read more