Question

Hi this is newbie in python, I want write a prioritized decorator which will decide which class instance has to be instantiated depending upon the priority value passed to the decorator.

# abstract class
class Base:
   def method1(self):
    pass

@deco(priority=1)
class A(Base):
    def method1(self):
        pass

@deco(priority=3)
class B(Base):
    def method1(self):
        pass

@deco(priority=2)
class C(B):
    def method1(self):
        pass

def return_class_obj():
# this method will return the object based upon the priority of the 
# class passed through decorator

Answer 1

It seems that you need something like this:

class Factory():
    registred = {}

    @classmethod
    def register(cls, priority):
        registred = cls.registred
        def inner(inner_cls):
            registred[priority] = inner_cls
            return inner_cls
        return inner
    @classmethod
    def get(cls):
        return min(cls.registred.items())[1]()

@Factory.register(3) 
class A():
    def test(self):
        print "A"

Factory.get().test()

@Factory.register(2)
class B():
    def test(self):
        print "B"

Factory.get().test()

@Factory.register(1)
class C(B):
    def test(self):
        print "C"

Factory.get().test()

This will output ABC