POC for Plugin model

poc.py

#!/usr/bin/python

import pprint
import inspect
from copy import deepcopy

class NimbisActionPluginMeta(type):
    # we use __init__ rather than __new__ here because we want
    # to modify attributes of the class *after* they have been
    # created

    def __init__(cls, name, bases, dct):
        if not hasattr(cls, 'registry'):
            cls.registry = {}
        for base in inspect.getmro(cls):
            empty_action = {
                'can_hooks': [],
                'frontend_hooks': [],
                'backend_hooks': []}
            if hasattr(base, 'actions'):
                #pprint.pprint(base.actions)
                for action in base.actions:
                    if action not in cls.registry:
                        cls.registry[action] = deepcopy(empty_action)
                    for hook_type in empty_action:
                        if hook_type not in base.actions[action]:
                            continue
                        for func in base.actions[action][hook_type]:
                            if func not in cls.registry[action][hook_type]:
                                cls.registry[action][hook_type].append(func)
        super(NimbisActionPluginMeta, cls).__init__(name, bases, dct)




class DesktopMixin(object):
    def one(self):
        print "one"

    def two(self):
        print "two"

    def three(self):
        print "three"

    def four(self):
        print "four"

    def nine(self):
        print "other nine"

    actions = {
        'change_resolution': {
            'can_hooks': (one,),
            'frontend_hooks': (three, four),},
        'start': {
            'can_hooks': (two, nine)}}

class StuffMixin(object):
    def nine(self):
        print "nine"

    actions = {
        'start': {
            'can_hooks': (nine,)}}

class Ec2Mixin(object):
    def five(self):
        print "five {0}".format(self.uuid)

    def six(self):
        print "six"

    def seven(self):
        print "seven"

    def eight(self):
        print "eight"

    actions = {
        'start': {
            'can_hooks': (five, six),
            'frontend_hooks': (seven, eight)}}

#class Session(DesktopMixin, StuffMixin):
class Session(StuffMixin, DesktopMixin):
    pass

class Ec2Session(Session,Ec2Mixin):
    __metaclass__ = NimbisActionPluginMeta
    def __init__(self):
        self.uuid = "my uuid"
        for can in self.registry['start']['can_hooks']:
            can(self)
        for front_end in self.registry['start']['frontend_hooks']:
            front_end(self)

class JustDesktop(Session):
    __metaclass__ = NimbisActionPluginMeta
    pass

#print "###### Session ######"
#session = Session()
#print "Session registry: {0}".format(session.registry)

print "###### Ec2Session ######"
ec2session = Ec2Session()
pprint.pprint(ec2session.registry)

print "###### JustDesktop ######"
jf = JustDesktop()
pprint.pprint(jf.registry)