def __init__(self, target, email, inviter, roles):
"""Creates a new `Invitation` on the `target` for `email`. The
invitation was created by `inviter` (userid). Roles are the given
additional roles for the user (email)
"""
# get the storage
storage = IInvitationStorage(target)
# set the attributes
self.email = email
self.inviter = inviter
self.set_target(target)
self.roles = roles
# generate the id, which sets it to self.iid
storage.generate_iid_for(self)
# register the invitation
storage.add_invitation(self)
