Listing all instance of a class

Question

I wrote a Python module, with several classes that inherit from a single class called MasterBlock. I want to import this module in a script, create several instance

Answer 1

Here's a way of doing that using a class variable:

class MasterBlock(object):
    instances = []
    def __init__(self):
        self.instances.append(self)
    def main(self):
        print "I am", self

class RandomA(MasterBlock):
    def __init__(self):
        super(RandomA, self).__init__()
        # other init...

class AnotherRandom(MasterBlock):
    def __init__(self):
        super(AnotherRandom, self).__init__()
        # other init...


a = RandomA()
b = AnotherRandom()
c = AnotherRandom()
# here I need to get list_of_instances=[a,b,c]

for instance in MasterBlock.instances:
    instance.main()

(you can make it simpler if you don't need __init__ in the subclasses)

output:

I am <__main__.RandomA object at 0x7faa46683610>
I am <__main__.AnotherRandom object at 0x7faa46683650>
I am <__main__.AnotherRandom object at 0x7faa46683690>