Refactor template namespace from render_string to its own method.

This method may be overridden as an alternative to overriding render_string
and adding to kwargs, or may be used directly to render templates
without going through render_string (as when templates are constructed
directly; see https://github.com/facebook/tornado/issues/564)

tornado/web.py

@@ -602,7 +602,20 @@ class RequestHandler(object):
             else:
                 loader = RequestHandler._template_loaders[template_path]
         t = loader.load(template_name)
-        args = dict(
+        namespace = self.get_template_namespace()
+        namespace.update(kwargs)
+        return t.generate(**namespace)
+
+    def get_template_namespace(self):
+        """Returns a dictionary to be used as the default template namespace.
+
+        May be overridden by subclasses to add or modify values.
+
+        The results of this method will be combined with additional
+        defaults in the `tornado.template` module and keyword arguments
+        to `render` or `render_string`.
+        """
+        namespace = dict(
             handler=self,
             request=self.request,
             current_user=self.current_user,
@@ -612,9 +625,8 @@ class RequestHandler(object):
             xsrf_form_html=self.xsrf_form_html,
             reverse_url=self.reverse_url
         )
-        args.update(self.ui)
-        args.update(kwargs)
-        return t.generate(**args)
+        namespace.update(self.ui)
+        return namespace
 
     def create_template_loader(self, template_path):
         settings = self.application.settings

website/sphinx/web.rst

@@ -47,6 +47,7 @@
    .. automethod:: RequestHandler.finish
    .. automethod:: RequestHandler.render
    .. automethod:: RequestHandler.render_string
+   .. automethod:: RequestHandler.get_template_namespace
    .. automethod:: RequestHandler.redirect
    .. automethod:: RequestHandler.send_error
    .. automethod:: RequestHandler.write_error