class RBACRole(object):

"""

This model provides core permission functionality.

"""

roles = {}

def __init__(self, name=None):

self.name = name

if not hasattr(self.__class__, 'parents'):

self.parents = set()

if not hasattr(self.__class__, 'children'):

self.children = set()

RBACRole.roles[name] = self

def add_parent(self, parent):

"""

Add a parent to this role,

and add role itself to the parent's children set.

you should override this function if neccessary.

"""

parent.children.add(self)

self.parents.add(parent)

def add_parents(self, *parents):

"""Add parents to this role. Also should override if neccessary.

Example::

editor_of_articles = RoleMixin('editor_of_articles')

editor_of_photonews = RoleMixin('editor_of_photonews')

editor_of_all = RoleMixin('editor_of_all')

editor_of_all.add_parents(editor_of_articles, editor_of_photonews)

:param parents: Parents to add.

"""

for parent in parents:

self.add_parent(parent)

def get_parents(self):

for parent in self.parents:

yield parent

for grandparent in parent.get_parents():

yield grandparent

def get_children(self):

for child in self.children:

yield child

for grandchild in child.get_children():

yield grandchild

@staticmethod

def get_by_name(name):

"""A static method to return the role which has the input name.

:param name: The name of role.

"""

return RBACRole.roles[name]

class RBACUserMixin(object):

"""

Provides basic role functionality to users.

"""

def get_roles(self):

roles = [RBACRole.roles["anonymous"]]

if self.role:

role = RBACRole.roles[self.role]

if role:

roles.append(role)

return roles