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There are methods that a subclass cannot override. For example, in Java, a method that is declared final in the super class cannot be overridden. Methods that are declared private or static cannot be overridden either because they are implicitly final. It is also impossible for a class that is declared final to become a super class. [9]
var x1 = 0; // A global variable, because it is not in any function let x2 = 0; // Also global, this time because it is not in any block function f {var z = 'foxes', r = 'birds'; // 2 local variables m = 'fish'; // global, because it wasn't declared anywhere before function child {var r = 'monkeys'; // This variable is local and does not affect the "birds" r of the parent function. z ...
An object's virtual method table will contain the addresses of the object's dynamically bound methods. Method calls are performed by fetching the method's address from the object's virtual method table. The virtual method table is the same for all objects belonging to the same class, and is therefore typically shared between them.
Contravariance of method parameter types in the subtype. Covariance of method return types in the subtype. New exceptions cannot be thrown by the methods in the subtype, except if they are subtypes of exceptions thrown by the methods of the supertype. In addition to the signature requirements, the subtype must meet a number of behavioural ...
For example, the addition (+) operator can be overloaded by implementing the method obj.__add__(self, other). Ruby allows operator overloading as syntactic sugar for simple method calls. Lua allows operator overloading as syntactic sugar for method calls with the added feature that if the first operand doesn't define that operator, the method ...
Alternatively, the Fluent plugin allows calling any static method as an extension method without using annotations, as long as the method signature matches. In Smalltalk, any code can add a method to any class at any time, by sending a method creation message (such as methodsFor: ) to the class the user wants to extend.
In Java, this will mean that the method in the derived class will implicitly override the method in the base class, even though that may not be the intent of the designers of either class. To mitigate this, C# requires that if a method is intended to override an inherited method, the override keyword must be specified. Otherwise, the method ...
In object-oriented programming, a covariant return type of a method is one that can be replaced by a "narrower" (derived) type when the method is overridden in a subclass. A notable language in which this is a fairly common paradigm is C++. C# supports return type covariance as of version 9.0. [1]