example-code-2e/control/coro_finally_demo.py
2015-02-17 10:07:07 -02:00

62 lines
1.5 KiB
Python

"""
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