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Python supports most object oriented programming (OOP) techniques. It allows polymorphism, not only within a class hierarchy but also by duck typing. Any object can be used for any type, and it will work so long as it has the proper methods and attributes. And everything in Python is an object, including classes, functions, numbers and modules.
The object methods include access to the object state (via an implicit or explicit parameter that references the object) whereas class methods do not. If the language supports inheritance , a class can be defined based on another class with all of its state and behavior plus additional state and behavior that further specializes the class.
Creation procedures must leave the newly initialized object in a state that satisfies the class invariant. [b] Although object creation involves some subtleties, [10] the creation of an attribute with a typical declaration x: T as expressed in a creation instruction create x.make consists of the following sequence of steps:
/*Ruby has three member variable types: class, class instance, and instance. */ class Dog # The class variable is defined within the class body with two at-signs # and describes data about all Dogs *and* their derived Dog breeds (if any) @@sniffs = true end mutt = Dog. new mutt. class. sniffs #=> true class Poodle < Dog # The "class instance variable" is defined within the class body with a ...
Duck typing is similar to, but distinct from, structural typing.Structural typing is a static typing system that determines type compatibility and equivalence by a type's structure, whereas duck typing is dynamic and determines type compatibility by only that part of a type's structure that is accessed during runtime.
[1]: 78 An object can model some part of reality or can be an invention of the design process whose collaborations with other such objects serve as the mechanisms that provide some higher-level behavior. Put another way, an object represents an individual, identifiable item, unit, or entity, either real or abstract, with a well-defined role in ...
Here, "object" referred to LISP atoms with identified properties (attributes). [ 5 ] [ 6 ] Another early example was Sketchpad created by Ivan Sutherland at MIT in 1960–1961. In the glossary of his technical report, Sutherland defined terms like "object" and "instance" (with the class concept covered by "master" or "definition"), albeit ...
In object-oriented programming, a metaclass is a class whose instances are classes themselves. Unlike ordinary classes, which define the behaviors of objects, metaclasses specify the behaviors of classes and their instances. Not all object-oriented programming languages support the concept of metaclasses. For those that do, the extent of ...