Add stream for CompositionView

sanic/router.py

@@ -352,4 +352,4 @@ class Router:
         :return: bool
         """
         handler = self.get(request)[0]
-        return handler.is_stream
+        return hasattr(handler, 'is_stream') and handler.is_stream

sanic/views.py

@@ -83,7 +83,8 @@ class CompositionView:
     def __init__(self):
         self.handlers = {}
 
-    def add(self, methods, handler):
+    def add(self, methods, handler, stream=False):
+        handler.is_stream = stream
         for method in methods:
             if method not in HTTP_METHODS:
                 raise InvalidUsage(