metaclass
Sign in to saveIn object-oriented programming, a metaclass is a class whose syntactic definitions are used for the syntactic definition of the 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 control metaclasses have over class behaviors varies. Metaclasses are often implemented by treating classes as first-class citizens, making a metaclass an object that creates and manages these classes. Each
Article
9 sectionsContents
- Python example
- In Smalltalk-80
- In Ruby
- In Objective-C
- C++ proposal
- Support in languages and tools
- See also
- References
- External links
In object-oriented programming, a metaclass is a class whose syntactic definitions are used for the syntactic definition of the 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 control metaclasses have over class behaviors varies. Metaclasses are often implemented by treating classes as first-class citizens, making a metaclass an object that creates and manages these classes. Each programming language adheres to its own metaobject protocol, which are the rules that determine interactions among objects, classes, and metaclasses. Metaclasses are utilized to automate code generation and to enhance framework development.
==Python example== In Python, the builtin class type is a metaclass. Consider this simple Python class: