Quick Check: Python With Statements and Context Managers

Review

1. Which method runs when a with statement successfully enters a context?

   This follows Python's context-manager protocol described in the lesson.
2. In `with Session() as state:`, what supplies the value assigned to state?

   This follows Python's context-manager protocol described in the lesson.
3. What happens to __exit__ when an exception is raised inside a successfully entered with block?

   This follows Python's context-manager protocol described in the lesson.
4. When does __exit__ suppress an exception from the with block?

   This follows Python's context-manager protocol described in the lesson.
5. How do multiple context managers in one with statement behave?

   This follows Python's context-manager protocol described in the lesson.
6. What does `with suppress(KeyError):` do if a KeyError is raised inside its with block?

   contextlib.suppress() suppresses only the exception types explicitly listed in the call. Exceptions not listed still propagate.
7. A function receives a stream that belongs to its caller. Which choice lets the function use with without taking responsibility for closing that stream?

   nullcontext(stream) returns the same object from __enter__ and performs no cleanup when the with block exits, so ownership remains with the caller.
8. A third-party reader has close() but no __enter__() or __exit__(). Which context manager ensures close() runs when the with block exits?

   contextlib.closing(reader) adapts an object that exposes close() but not the context-manager protocol. It calls close() when the block exits, even if the body raises; it does not suppress the exception.