abc.py

abstract class

import abc

class PluginBase(object):
    __metaclass__ = abc.ABCMeta

    def __init__(self):
        self.base = 'base_info'

    @abc.abstractmethod
    def load(self, input):
        """Retrieve data from the input source and return an object."""
        return

    @abc.abstractmethod
    def save(self, output, data):
        """Save the data object to the output."""
        return


class SubclassImplementation(PluginBase):

    def __init__(self):
        super(SubclassImplementation, self).__init__()
        self.base = 'james'

    def load(self, input):
        print self.base
        return True

    def asave(self, output, data):
        return True

if __name__ == '__main__':
    print 'Subclass:', issubclass(SubclassImplementation, PluginBase)
    print 'Instance:', isinstance(SubclassImplementation(), PluginBase)
    obj = SubclassImplementation()
    obj.load('input')