class A { public: int x; protected: int y; private: int z; }; class B : public A { // x is public // y is protected // z is not accessible from B }; class C : protected A { // x is protected // y is protected // z is not accessible from …
class A CONST = ‘A’ def initialize puts self.class::CONST end end class B < A CONST = ‘B’ end A.new # => ‘A’ B.new # => ‘B’
In Swift with struct you can create protocol for common task and also implement default implementation using protocol extension. protocol Vehicle { var model: String { get set } var color: String { get set } } //Common Implementation using protocol extension extension Vehicle { static func parseVehicleFields(jsonDict: [String:Any]) -> (String, String) { let model …
I think you are taking the meaning of multiple inheritance in a wrong way. Probably what you have in mind as multiple inheritance is like this: class A inherits class B class B inherits class C If so, then that is wrong. That is not what multiple inheritance is, and Ruby has no problem with …
Tony Park gave an answer which is pretty close to the truth. The C++ committee basically didn’t think it was worth the effort to make unions a strong part of C++, similarly to the treatment of arrays as legacy stuff we had to inherit from C but didn’t really want. Unions have problems: if we …
A contract in in a Java class is similar to a contract in the real world – In non-technical terms: It’s an agreement that the class will expose certain methods, certain properties, and certain behaviors. More technical, from here: (bold added by me) Wouldn’t it be nice if all Java classes that you use, including …
According to the Hibernate Reference Documentation it should be possible to mix different inheritance mapping strategies when using Hibernate’s XML-Metadata (…) Actually, it’s not really supported, they are “cheating” using a secondary table to switch from the single table strategy in the example of the documentation. Quoting Java Persistence with Hibernate: You can map whole …
When foo receives a FooBase reference, the compiler doesn’t know whether the argument is a descendant of Foo, so it has to assume it’s not. Foo has access to inherited protected members of other Foo objects, not all other sibling classes. Consider this code: class FooSibling: public FooBase { }; FooSibling sib; Foo f; f.foo(sib); …
I would say that the reason is to have a common API for all objects in java to supports basic functionality like synchronization – wait, notify, notifyAll garbage collection – finalize collection support – hashCode, equals object cloning – clone And every object has a class it belongs to – getClass can represent itself as …
Rails supports Single Table Inheritance. From the AR docs: Active Record allows inheritance by storing the name of the class in a column that by default is named “type” (can be changed by overwriting Base.inheritance_column). This means that an inheritance looking like this: class Company < ActiveRecord::Base; end class Firm < Company; end class Client …