class decorators with staticmethod

foo.py

from tornado.web import RequestHandler

class BaseHandler(RequestHandler):
    
    def prepare(self):
        self.current_user = None
    
    def _render_401(self):
        if self._req_was_rest:
            self.set_status(401)
            self.set_header('WWW-Authenticate', 
            'Bearer realm="{}"'.format(
                self.request.uri
            ))
            self.finish()
        else:
            self.redirect(self._CONFIG['auth'] + 
                '/sso/auth?appname={}&orig_uri={}'.format(
                    self._CONFIG['app_name'], 
                    urlparse.quote(self.request.full_url())
                )
            )

class AuthorizedHandler(BaseHandler):

    @staticmethod
    def requires_login(method):
        def decorated(self, *args, **kwargs):
            if not self.current_user:
                self._render_401()
            else:
                return method(self, *args, **kwargs)    
        return decorated

class FooHandler(AuthorizedHandler):
    
    @AuthorizedHandler.requires_login
    def get(self, *args, **kwargs):
        self.render('foo.html')

I came from https://stackoverflow.com/questions/13852138/how-can-i-define-decorator-method-inside-class
This is a nice pattern! I'll probably use it everywhere now. =)

I came from the same SO post. This pattern does not work correctly with positional arguments as written. Self needs to be treated as an implicit positional argument, then pulled out from the variadic args.

    @staticmethod
    def requires_login(method):
        def decorated(*args, **kwargs):
            self=args[0]
            if not self.current_user:
                self._render_401()
            else:
                return method(self, *args, **kwargs)    
        return decorated