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In the delegate pattern, this is instead accomplished by explicitly passing the original object to the delegate, as an argument to a method. [1] " Delegation" is often used loosely to refer to the distinct concept of forwarding , where the sending object simply uses the corresponding member on the receiving object, evaluated in the context of ...
Thus, the obligatory first parameter of instance methods serves as this; this parameter is conventionally named self, but can be named anything. In class methods (created with the classmethod decorator), the first argument refers to the class object itself, and is conventionally called cls; these are primarily used for inheritable constructors ...
Decorator UML class diagram. The decorator pattern can be used to extend (decorate) the functionality of a certain object statically, or in some cases at run-time, independently of other instances of the same class, provided some groundwork is done at design time. This is achieved by designing a new Decorator class that wraps the original class ...
Python allows the creation of class methods and static methods via the use of the @classmethod and @staticmethod decorators. The first argument to a class method is the class object instead of the self-reference to the instance. A static method has no special first argument. Neither the instance, nor the class object is passed to a static method.
In software engineering, the adapter pattern is a software design pattern (also known as wrapper, an alternative naming shared with the decorator pattern) that allows the interface of an existing class to be used as another interface. [1]
Quoted from Python_syntax_and_semantics#Decorators: "Despite the name, Python decorators are not an implementation of the decorator pattern." 195.169.128.3 08:38, 29 July 2009 (UTC) I doubt the Python example even is an example of the pattern as the decoration occurs during the definition of the class itself, and not at 'run-time'.
Mixin programming is a style of software development, in which units of functionality are created in a class and then mixed in with other classes. [6] A mixin class acts as the parent class, containing the desired functionality. A subclass can then inherit or simply reuse this functionality, but not as a means of specialization.
It should be possible to define a new operation for (some) classes of an object structure without changing the classes. When new operations are needed frequently and the object structure consists of many unrelated classes, it's inflexible to add new subclasses each time a new operation is required because "[..] distributing all these operations across the various node classes leads to a system ...