updated from Atlas

16-coroutine/coro_finally_demo.py

@@ -0,0 +1,61 @@
+"""
+Second coroutine closing demonstration::
+
+    >>> fin_coro = demo_finally()
+    >>> next(fin_coro)
+    -> coroutine started
+    >>> fin_coro.send(11)
+    -> coroutine received: 11
+    >>> fin_coro.send(22)
+    -> coroutine received: 22
+    >>> fin_coro.close()
+    -> coroutine ending
+
+
+Second coroutine not handling exception::
+
+    >>> fin_coro = demo_finally()
+    >>> next(fin_coro)
+    -> coroutine started
+    >>> fin_coro.send(11)
+    -> coroutine received: 11
+    >>> fin_coro.throw(ZeroDivisionError)  # doctest: +SKIP
+    -> coroutine ending
+    Traceback (most recent call last):
+      File "<stdin>", line 1, in <module>
+      File "coro_exception_demos.py", line 109, in demo_finally
+        print('-> coroutine received: {!r}'.format(x))
+    ZeroDivisionError
+
+
+The last test above must be skipped because the output '-> coroutine ending'
+is not detected by doctest, which raises a false error. However, if you
+run this file as shown below, you'll see that output "leak" into standard
+output::
+
+
+    $ python3 -m doctest coro_exception_demos.py
+    -> coroutine ending
+
+"""
+
+
+# BEGIN EX_CORO_FINALLY
+class DemoException(Exception):
+    """An exception type for the demonstration."""
+
+
+def demo_finally():
+    print('-> coroutine started')
+    try:
+        while True:
+            try:
+                x = yield
+            except DemoException:
+                print('*** DemoException handled. Continuing...')
+            else:
+                print('-> coroutine received: {!r}'.format(x))
+    finally:
+        print('-> coroutine ending')
+
+# END EX_CORO_FINALLY