Context Managers (Slideshow)

Problem

• Resource cleanup

• Python is garbage collected

• Cleanup does happen but nobody can say when ⟶ not deterministic

Solution: The with Statement

with open('/etc/passwd') as f:
    ... use f ...

• Interpreter “talks to” user-supplied code

• Much like the iterator protocol

• Many creative uses

• contextlib: pool of creativity, https://docs.python.org/3/library/contextlib.html