Editing Class (computer programming) (section)

===Open<span class="anchor" id="Open class"></span>===

An open class can be changed. Typically, an [[executable program]] cannot be changed by customers. Developers can often change some classes, but typically cannot change standard or built-in ones. In [[Ruby (programming language)#Open classes|Ruby]], all classes are open. In [[Python (programming language)|Python]], classes can be created at runtime, and all can be modified afterward.<ref>{{cite web|title=9. Classes|url=https://docs.python.org/3.3/tutorial/classes.html|website=The Python Tutorial|publisher=Python.org|access-date=3 March 2018|quote=As is true for modules, classes partake of the dynamic nature of Python: they are created at runtime, and can be modified further after creation.}}</ref> [[Objective-C#Categories|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.