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In computer programming, variable shadowing occurs when a variable declared within a certain scope (decision block, method, or inner class) has the same name as a variable declared in an outer scope. At the level of identifiers (names, rather than variables), this is known as name masking .
Method overriding, in object-oriented programming, is a language feature that allows a subclass or child class to provide a specific implementation of a method that is already provided by one of its superclasses or parent classes.
The scoped subtree in an element is called a shadow tree. The element the shadow tree is attached to is called a shadow host. [6] A Shadow DOM must always be connected to an existing element, either through attaching it as a literal element or through scripting. In JavaScript, Shadow DOMs are attached to an element using Element.attachShadow(). [7]
By the usual subtyping rule for function types, this means that the overriding method should return a more specific type (return type covariance) and accept a more general argument (parameter type contravariance). In UML notation, the possibilities are as follows (where Class B is the subclass that extends Class A which is the superclass):
Block scope can be used for shadowing. In this example, inside the block the auxiliary variable could also have been called n, shadowing the parameter name, but this is considered poor style due to the potential for errors. Furthermore, some descendants of C, such as Java and C#, despite having support for block scope (in that a local variable ...
Manual override, a function where an automated system is placed under manual control; Method overriding, a subclassing feature in object-oriented programming languages.
Virtual method tables also only work if dispatching is constrained to a known set of methods, so they can be placed in a simple array built at compile time, in contrast to duck typing languages (such as Smalltalk, Python or JavaScript).
The same function name is used for more than one function definition in a particular module, class or namespace; The functions must have different type signatures, i.e. differ in the number or the types of their formal parameters (as in C++) or additionally in their return type (as in Ada).