Add a warning for soon to be deprecated `ctx` use in `@stream` func

tractor/_streaming.py

@@ -57,6 +57,9 @@ class Context:
         timeout quickly to sidestep 2-generals...
 
         """
+        assert self._portal, (
+            "No portal found, this is likely a callee side context")
+
         cid = self.cid
         with trio.move_on_after(0.5) as cs:
             cs.shield = True
@@ -95,7 +98,20 @@ def stream(func):
     """
     func._tractor_stream_function = True
     sig = inspect.signature(func)
-    if 'ctx' not in sig.parameters:
+    params = sig.parameters
+    if 'stream' not in params and 'ctx' in params:
+        warnings.warn(
+            "`@tractr.stream decorated funcs should now declare a `stream` "
+            " arg, `ctx` is now designated for use with @tractor.context",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+
+    if (
+        'ctx' not in params and
+        'to_trio' not in params and
+        'stream' not in params
+    ):
         raise TypeError(
             "The first argument to the stream function "
             f"{func.__name__} must be `ctx: tractor.Context`"
@@ -120,7 +136,7 @@ class ReceiveMsgStream(trio.abc.ReceiveChannel):
         self,
         ctx: Context,
         rx_chan: trio.abc.ReceiveChannel,
-        portal: 'Portal',  # noqa
+        portal: 'Portal',  # type: ignore # noqa
     ) -> None:
         self._ctx = ctx
         self._rx_chan = rx_chan
@@ -152,7 +168,7 @@ class ReceiveMsgStream(trio.abc.ReceiveChannel):
                 # raise the error message
                 raise unpack_error(msg, self._portal.channel)
 
-        except trio.ClosedResourceError:
+        except (trio.ClosedResourceError, StopAsyncIteration):
             # XXX: this indicates that a `stop` message was
             # sent by the far side of the underlying channel.
             # Currently this is triggered by calling ``.aclose()`` on
@@ -184,7 +200,7 @@ class ReceiveMsgStream(trio.abc.ReceiveChannel):
     @contextmanager
     def shield(
         self
-    ) -> Iterator['ReceiveStream']:  # noqa
+    ) -> Iterator['ReceiveMsgStream']:  # noqa
         """Shield this stream's underlying channel such that a local consumer task
         can be cancelled (and possibly restarted) using ``trio.Cancelled``.
 
@@ -243,4 +259,4 @@ class MsgStream(ReceiveMsgStream, trio.abc.Channel):
         self,
         data: Any
     ) -> None:
-        await self._chan.send({'yield': data, 'cid': self._cid})
+        await self._ctx.chan.send({'yield': data, 'cid': self._ctx.cid})