feat: make Function an ASGI callable

cmd/fhttp/main.py

@@ -2,21 +2,28 @@
 import logging
 from func_python.http import serve
 
+# Set the default logging level to INFO
 logging.basicConfig(level=logging.INFO)
 
+# Allow this test to be either instanced (default) or --static
+# to test the two different primary method signatures supported in the
+# final Function.
 parser = argparse.ArgumentParser(description='Serve a Test Function')
 parser.add_argument('--static', action='store_true',
                     help='Serve the example static handler (default is to '
                          'instantiate and serve the example class)')
 args = parser.parse_args()
 
 
+# Example static handler.
+# Enable with --static
+# Must be named exactly "handle"
 async def handle(scope, receive, send):
     """ handle is an example of a static handler which can be sent to the
     middleware as a funciton.  It will be wrapped in a default Funciton
     instance before being served as an ASGI application.
     """
-    logging.info("OK: static")
+    logging.info("OK: static!!")
 
     await send({
         'type': 'http.response.start',
@@ -29,17 +36,19 @@ async def handle(scope, receive, send):
     })
 
 
-class Function:
+# Example instanced handler
+# This is the default expected by this test.
+# The class can be named anything.  See "new" below.
+class MyFunction:
     """ Function is an example of a functioon instance.  The structure
     implements the function which will be deployed as a network service.
     The class name can be changed.  The only required method is "handle".
     """
-
-    async def handle(self, scope, receive, send):
+    async def __call__(self, scope, receive, send):
         """ handle is the only method which must be implemented by the
         function instance for it to be served as an ASGI handler.
         """
-        logging.info("OK: instanced")
+        logging.info("OK: instanced!!")
 
         await send({
             'type': 'http.response.start',
@@ -52,16 +61,21 @@ async def handle(self, scope, receive, send):
         })
 
 
+# Funciton instance constructor
+# expected to be named exactly "new"
+# Must return a callable which conforms to the ASGI spec.
 def new():
     """ new is the factory function (or constructor) which will create
     a new function instance when invoked.  This must be named "new", and the
     structure returned must include a method named "handle" which implements
     the ASGI specification's method signature.  The name of the class itself
     can be changed.
     """
-    return Function()
+    return MyFunction()
 
 
+# Run the example.
+# Start either the static or instanced handler depending on flag --static
 if __name__ == "__main__":
     if args.static:
         logging.info("Starting static handler")

src/func_python/http.py

@@ -34,6 +34,10 @@ class DefaultFunction:
     def __init__(self, handler):
         self.handle = handler
 
+    async def __call__(self, scope, receive, send):
+        # delegate to the handler implementation provided during construction.
+        await self.handle (scope, receive, send) 
+
 
 class ASGIApplication():
     def __init__(self, f):
@@ -105,8 +109,8 @@ async def __call__(self, scope, receive, send):
             elif scope['path'] == '/health/readiness':
                 await self.handle_readiness(scope, receive, send)
             else:
-                if hasattr(self.f, "handle"):
-                    await self.f.handle(scope, receive, send)
+                if callable(self.f):
+                    await self.f(scope, receive, send)
                 else:
                     raise Exception("function does not implement handle")
         except Exception as e: