L4·OOP & Errors

🚪Context Managers (with)

Guaranteed setup and teardown.

withcontext__enter____exit__

§ 1The protocol

__enter__(self) runs at the start of with. __exit__(self, exc_type, exc, tb) runs at the end, even on exception.

§ 2contextlib.contextmanager

Turn a generator with a single yield into a context manager.

Example

1from contextlib import contextmanager
2
3@contextmanager
4def tag(name):
5    print(f"<{name}>")
6    yield
7    print(f"</{name}>")
8
9with tag("h1"):
10    print("Hello")

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Iterators & Generators