UsingMixInsWithPython - BioHackersNet

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. OOP의 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.

Python은 훌륭한 OOP언어로서, 다중상속 및 dynamic class binding을 지원한다.

   1 >>>class Friendly:
   2 ... def hello(self):
   3 ... print 'Hello'
   4 ...
   5 >>> class Person:
   6 ... pass
   7 ...
   8 >>> p = Person()
   9 >>> Person.__bases__ += (Friendly,)
  10 >>> p.hello()
  11 Hello

   1 import types
   2 def MixIn(pyClass, mixInClass, makeAncestor=0):
   3    if makeAncestor:
   4      if mixInClass not in pyClass.__bases__:
   5         pyClass.__bases__ = (mixInClass,) + pyClass.__bases__
   6    else:
   7      # Recursively traverse the mix-in ancestor
   8      # classes in order to support inheritance
   9      baseClasses = list(mixInClass.__bases__)
  10      baseClasses.reverse()
  11      for baseClass in baseClasses:
  12         MixIn(pyClass, baseClass)
  13      # Install the mix-in methods into the class
  14      for name in dir(mixInClass):
  15         if not name.startswith('__'):
  16         # skip private members
  17            member = getattr(mixInClass, name)
  18            if type(member) is types.MethodType:
  19                member = member.im_func
  20            setattr(pyClass, name, member)

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