Modern Python Standard Library Cookbook

How to do it...

For this recipe, the following steps are to be performed:

1. contextlib provides features related to context managers, contextlib.contextmanager can make it very easy to write context managers:

@contextlib.contextmanager
def logentrance():
    print('Enter')
    yield
    print('Exit')

2. Then the context manager created can be used like any other context manager:

>>> with logentrance():
>>>    print('This is inside')
Enter
This is inside
Exit

3. Exceptions raised within the wrapped block will be propagated to the context manager, so it's possible to handle them with a standard try:except:finally: clause and do any proper cleanup:

@contextlib.contextmanager def logentrance(): print('Enter') try: yield except: print('Exception') raise finally: ...