updated from Atlas

16-coroutine/coro_exc_demo.py

@@ -0,0 +1,66 @@
+"""
+Coroutine closing demonstration::
+
+# BEGIN DEMO_CORO_EXC_1
+    >>> exc_coro = demo_exc_handling()
+    >>> next(exc_coro)
+    -> coroutine started
+    >>> exc_coro.send(11)
+    -> coroutine received: 11
+    >>> exc_coro.send(22)
+    -> coroutine received: 22
+    >>> exc_coro.close()
+    >>> from inspect import getgeneratorstate
+    >>> getgeneratorstate(exc_coro)
+    'GEN_CLOSED'
+
+# END DEMO_CORO_EXC_1
+
+Coroutine handling exception::
+
+# BEGIN DEMO_CORO_EXC_2
+    >>> exc_coro = demo_exc_handling()
+    >>> next(exc_coro)
+    -> coroutine started
+    >>> exc_coro.send(11)
+    -> coroutine received: 11
+    >>> exc_coro.throw(DemoException)
+    *** DemoException handled. Continuing...
+    >>> getgeneratorstate(exc_coro)
+    'GEN_SUSPENDED'
+
+# END DEMO_CORO_EXC_2
+
+Coroutine not handling exception::
+
+# BEGIN DEMO_CORO_EXC_3
+    >>> exc_coro = demo_exc_handling()
+    >>> next(exc_coro)
+    -> coroutine started
+    >>> exc_coro.send(11)
+    -> coroutine received: 11
+    >>> exc_coro.throw(ZeroDivisionError)
+    Traceback (most recent call last):
+      ...
+    ZeroDivisionError
+    >>> getgeneratorstate(exc_coro)
+    'GEN_CLOSED'
+
+# END DEMO_CORO_EXC_3
+"""
+
+# BEGIN EX_CORO_EXC
+class DemoException(Exception):
+    """An exception type for the demonstration."""
+
+def demo_exc_handling():
+    print('-> coroutine started')
+    while True:
+        try:
+            x = yield
+        except DemoException:  # <1>
+            print('*** DemoException handled. Continuing...')
+        else:  # <2>
+            print('-> coroutine received: {!r}'.format(x))
+    raise RuntimeError('This line should never run.')  # <3>
+# END EX_CORO_EXC