Suggested improvements of Flask-Principal

principal.py

import logging
log = logging.getLogger(__name__)

from functools import wraps
from flask import session, request, g

from flaskext.principal import Principal as RealPrincipal, identity_loaded, Identity, AnonymousIdentity

__all__ = ['Principal']

class UserIdentity(Identity):
	def __init__(self, user, auth_type=''):
		super(UserIdentity, self).__init__(user.id, auth_type=auth_type)
		self.user = user

	@property
	def id(self):
		return self.name

def wrap_identity(f):
	@wraps(f)
	def decorate(*args, **kwargs):
		result = f(*args, **kwargs)
		user, auth_type = result or (None, None)
		if user is not None:
			return UserIdentity(user, auth_type)
	return decorate

class Principal(RealPrincipal):
	def __init__(self, app=None):
		super(Principal, self).__init__(use_sessions=False)
		if app is not None:
			self.init_app(app)

		self.get_user_by_id = lambda id: None
		self.get_user_by_login = lambda login, password: None

	def init_app(self, app):
		self._init_app(app)

		self.lowercase_login = app.config.get('AUTHENTIFIER_LOWERCASE_LOGIN', False)
		loaders              = app.config.get('AUTHENTIFIER_AUTH_TYPES', ['form', 'http-basic', 'session'])

		if 'form' in loaders:
			self.login_paths = app.config['AUTHENTIFIER_LOGIN_PATHS']
			self.identity_loader(self.authenticate_form)

		if 'http-basic' in loaders:
			self.identity_loader(self.authenticate_http_basic)

		if 'session' in loaders:
			self.identity_loader(self.authenticate_session)
			self.identity_saver(self.remember_session)

		app.before_request(lambda: self.ensure_user(g.identity))
		identity_loaded.connect_via(app)(lambda app, identity: self.ensure_user(identity))

	# Decorators
	def user_by_id(self, f):
		self.get_user_by_id = f
		return f

	def user_by_login(self, f):
		self.get_user_by_login = f
		return f

	# Public API
	def logout(self):
		self.set_identity(AnonymousIdentity())

	def login(self, user):
		self.set_identity(UserIdentity(user, 'manual'))

	# Helpers for events
	@wrap_identity
	def authenticate_form(self):
		if request.path in self.login_paths and request.method == 'POST':
			login, password = request.form.get('login', u''), request.form.get('password', u'')

			if self.lowercase_login:
				login = login.lower()

			if login:
				return (self.get_user_by_login(login, password), 'form')

	@wrap_identity
	def authenticate_http_basic(self):
		a = request.authorization
		if a and a['username']:
			return (self.get_user_by_login(a['username'], a['password']), 'http-basic')

	@wrap_identity
	def authenticate_session(self):
		uid = session.get('uid')
		if uid:
			return (self.get_user_by_id(uid), 'session')

	def remember_session(self, identity):
		if not isinstance(identity, AnonymousIdentity):
			session['uid'] = identity.id
		elif 'uid' in session:
			del session['uid']
		session.modified = True

	def ensure_user(self, identity):
		g.user = getattr(identity, 'user', None)