By: Pythongg

Pythongg — Mon, 18 Apr 2011 00:32:08 +0000

So if you were to do what you said but instead had WindowsFoo and Linux foo be in two different files, how could you achieve the same result? __subclasses__() is empty if WindowsFoo and LinuxFoo are not in the same file

I’m asking because I’m trying to implement the same sort of idea but I want my subclasses to be in different files

By: Quikee

Quikee — Mon, 11 Feb 2008 20:25:00 +0000

I don't know.. I prefer the below example mainly because it is without metaclass hackery (Foo magicly has some functionality but does not inherit from anything), but not quite so different:

import sys

class FooBase(object):
	def __new__(cls, *arguments, **keyword):
		for subclass in FooBase.__subclasses__():
			if subclass.platform == sys.platform:
				return super(cls, subclass).__new__(subclass, *arguments, **keyword)
		raise Exception, 'Platform not supported'
	
	def say_foo(self):
		print 'foo'

	def say_platform_foo(self):
		raise NotImplementedError

class WindowsFoo(FooBase):
	platform = 'win32'
	
	def say_platform_foo(self):
		print 'win32 foo'

class LinuxFoo(FooBase):
	platform = 'linux2'
	
	def say_platform_foo(self):
		print 'linux foo'

if __name__ == '__main__':
	foo = FooBase()
	foo.say_platform_foo()
	def say_platform_foo(self):
		print 'linux foo'

Comments on: Python factory-like type instances

By: Pythongg

By: Quikee