Suppport yield from a trollius coroutine in an asyncio coroutine

3 files changed, 47 insertions, 20 deletions

diff --git a/tests/test_tasks.py b/tests/test_tasks.py
index befe050..0381852 100644
--- a/tests/test_tasks.py
+++ b/tests/test_tasks.py
@@ -1451,7 +1451,7 @@ class TaskTests(test_utils.TestCase):
             cw.send(None)
             try:
                 cw.send(arg)
-            except Return as ex:
+            except StopIteration as ex:
                 return ex.value
             else:
                 raise AssertionError('StopIteration was expected')
diff --git a/trollius/coroutines.py b/trollius/coroutines.py
index 0a42f67..ee610c2 100644
--- a/trollius/coroutines.py
+++ b/trollius/coroutines.py
@@ -2,8 +2,13 @@ import functools
 import inspect
 import os
 import sys
+try:
+    import asyncio
+except ImportError:
+    asyncio = None
 
-from trollius import futures
+from . import compat
+from . import futures
 from .log import logger
 
 # If you set _DEBUG to true, @coroutine will wrap the resulting
@@ -19,20 +24,37 @@ _DEBUG = (not sys.flags.ignore_environment
           and bool(os.environ.get('PYTHONASYNCIODEBUG')))
 
 
-class Return(StopIteration):
-    def __init__(self, *value):
-        StopIteration.__init__(self)
-        if not value:
-            self.value = None
-        elif len(value) == 1:
-            self.value = value[0]
+if compat.PY33:
+    # Don't use the Return class on Python 3.3 and later to support asyncio
+    # coroutines (to avoid the warning emited in Return destructor).
+    #
+    # The problem is that Return inherits from StopIteration.  "yield from
+    # trollius_coroutine". Task._step() does not receive the Return exception,
+    # because "yield from" handles it internally. So it's not possible to set
+    # the raised attribute to True to avoid the warning in Return destructor.
+    def Return(*args):
+        if not args:
+            value = None
+        elif len(args) == 1:
+            value = args[0]
         else:
-            self.value = value
-        self.raised = False
-
-    def __del__(self):
-        if not self.raised:
-            logger.error('Return(%r) used without raise', self.value)
+            value = args
+        return StopIteration(value)
+else:
+    class Return(StopIteration):
+        def __init__(self, *args):
+            StopIteration.__init__(self)
+            if not args:
+                self.value = None
+            elif len(args) == 1:
+                self.value = args[0]
+            else:
+                self.value = args
+            self.raised = False
+
+        def __del__(self):
+            if not self.raised:
+                logger.error('Return(%r) used without raise', self.value)
 
 
 class CoroWrapper(object):
diff --git a/trollius/tasks.py b/trollius/tasks.py
index d97ee03..993cf0b 100644
--- a/trollius/tasks.py
+++ b/trollius/tasks.py
@@ -21,6 +21,7 @@ try:
 except ImportError:
     asyncio = None
 
+from . import compat
 from . import events
 from . import executor
 from . import futures
@@ -232,12 +233,16 @@ class Task(futures.Future):
                 result = coro.send(value)
             else:
                 result = next(coro)
-        except Return as exc:
-            exc.raised = True
-            self.set_result(exc.value)
         except StopIteration as exc:
-            # asyncio Task object? get the result of the coroutine
-            result = getattr(exc, 'value', None)
+            if compat.PY33:
+                # asyncio Task object? get the result of the coroutine
+                result = exc.value
+            else:
+                if isinstance(exc, Return):
+                    exc.raised = True
+                    result = exc.value
+                else:
+                    result = None
             self.set_result(result)
         except futures.CancelledError as exc:
             super(Task, self).cancel()  # I.e., Future.cancel(self).