#!/usr/bin/python


class Vars(object):
    variables = {}

    def read_vars(self):
        print("Reading group_vars/%s" % self.__class__.__name__)

        subclasses = self.__class__.__subclasses__()

        for subclass in subclasses:
            if subclass.hosts is None:
                print(" - Merging with group_vars/%s" % subclass.__name__)


class all(Vars):
    hosts = None


# [ DEV ]

class dev(all):
    hosts = ['host0']


# [ PREPROD ]

class preprod(all):
    hosts = None


class preprod_app1(preprod):
    hosts = ['host1', 'host2', 'host3']


# [ PROD ]

class prod(all):
    hosts = None


class prod_app1(prod):
    hosts = ['host4', 'host5', 'host6']


# [ TEMPLATES ]

class template_app1(preprod_app1, prod_app1):
    hosts = None


def main():
    dv = dev()
    dv.read_vars()

    pp = preprod_app1()
    pp.read_vars()

    pr = preprod_app1()
    pr.read_vars()


if __name__ == '__main__':
    main()

"""
### Output:
Reading group_vars/dev
Reading group_vars/preprod_app1
 - Merging with group_vars/template_app1
Reading group_vars/preprod_app1
 - Merging with group_vars/template_app1

### That corresponds with this inventory file:
[preprod:children]
preprod_app1

[preprod_app1]
host1
host2
host3

[preprod_app1:children]
template_app1

[prod:children]
prod_app1_tmp

[prod_app1]
host4
host5
host6

[prod_app1:children]
template_app1

[template_app1]
# Is empty
"""