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__exit__ method

As explained in Python Workout: 50 ten-minute exercises

The __exit__ method is a special Python method invoked when execution leaves a context manager and commonly performs cleanup or handles exceptions.

The __exit__ method runs when execution leaves a with block. It lets a context-managed object restore or change state, making cleanup happen at the boundary of the context rather than in separate manual code. section 5.10

File cleanup with with

with open('myfile.txt', 'w') as f: f.write('abc\n') f.write('def\n') When this block ends, the file object's __exit__ method flushes and closes the file. The same protocol can support database transactions, locked sections, and user-defined context-manager classes. section 5.10

How Python Workout: 50 ten-minute exercises covers it

How deep it goes
Explains when __exit__ runs and what cleanup it performs, but does not detail its method signature or exception arguments.
Examples
Uses a with open call that writes two lines and relies on __exit__ to flush and close the file.
What it assumes
Assumes familiarity with Python objects and with statements while connecting __exit__ to the paired __enter__ method.
What you can do after
Understand how with-triggered cleanup works and recognize where custom context-manager classes can apply the protocol.
How it connects
Connects __exit__ to context managers, __enter__, with statements, file handling, database transactions, and locking.
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Related concepts

This explainer was generated by Manning's knowledge graph from the text of Python Workout: 50 ten-minute exercises. The section links point to the parts of the book it draws on.