LinuxJournal, April 01, 2001

http://www.linuxjournal.com/article.php?sid=4540

Mix-in programming 은 프로그래밍 스타일의 한가지로서, 특정 기능을 지니는 단위(class)를 다른 단위와 섞어쓰는 기법이다. [[OOP]]의 MultipleInheritance가 사용된다.

There are several reasons to use mix-ins:
 * extend existing classes in new areas without having to edit,
 * maintain or merge with their source code
 * keep project components (such as domain frameworks and interface frameworks) separate
 * they ease the creation of new classes by providing a grab bag of functionalities that can be combined as needed
 * overcome a limitation of subclassing, whereby a new subclass has no effect if objects of the original class are still being created in other parts of the software.

[[Python]]은 훌륭한 [[OOP]]언어로서, 다중상속 및 dynamic class binding을 지원한다.

{{{#!python
>>>class Friendly:
... def hello(self):
... print 'Hello'
...
>>> class Person:
... pass
...
>>> p = Person()
>>> Person.__bases__ += (Friendly,)
>>> p.hello()
Hello
}}}

{{{#!python
import types
def MixIn(pyClass, mixInClass, makeAncestor=0):
   if makeAncestor:
     if mixInClass not in pyClass.__bases__:
        pyClass.__bases__ = (mixInClass,) + pyClass.__bases__
   else:
     # Recursively traverse the mix-in ancestor
     # classes in order to support inheritance
     baseClasses = list(mixInClass.__bases__)
     baseClasses.reverse()
     for baseClass in baseClasses:
        MixIn(pyClass, baseClass)
     # Install the mix-in methods into the class
     for name in dir(mixInClass):
        if not name.startswith('__'):
        # skip private members
           member = getattr(mixInClass, name)
           if type(member) is types.MethodType:
               member = member.im_func
           setattr(pyClass, name, member)

}}}

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