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The decorator pattern is a design pattern used in statically-typed object-oriented programming languages to allow functionality to be added to objects at run time; Python decorators add functionality to functions and methods at definition time, and thus are a higher-level construct than decorator-pattern classes.
In the Decorator class, add a Component pointer as a field; In the Decorator class, pass a Component to the Decorator constructor to initialize the Component pointer; In the Decorator class, forward all Component methods to the Component pointer; and; In the ConcreteDecorator class, override any Component method(s) whose behavior needs to be ...
A function object solves those problems since the function is really a façade for a full object, carrying its own state. Many modern (and some older) languages, e.g. C++, Eiffel, Groovy, Lisp, Smalltalk, Perl, PHP, Python, Ruby, Scala, and many others, support first-class function objects and may even make significant use of them. [3]
In Ruby, all classes are open. In Python, classes can be created at runtime, and all can be modified afterward. [43] Objective-C categories permit the programmer to add methods to an existing class without the need to recompile that class or even have access to its source code.
Class Cat defines a virtual function named speak, so its subclasses may provide an appropriate implementation (e.g. either meow or roar). When the program calls the speak function on a Cat reference (which can refer to an instance of Cat , or an instance of HouseCat or Lion ), the code must be able to determine which implementation of the ...
The common practice of documenting a code object at the head of its definition is captured by the addition of docstring syntax in the Python language. The docstring for a Python code object (a module, class, or function) is the first statement of that code object, immediately following the definition (the 'def' or 'class' statement).
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.
In computer science, a programming language is said to have first-class functions if it treats functions as first-class citizens. This means the language supports passing functions as arguments to other functions, returning them as the values from other functions, and assigning them to variables or storing them in data structures. [ 1 ]