Module 10

Protocols and Advanced Iteration

Build memory-efficient iterators, custom context managers, and type-annotated code.

Coding practice Module exam Cheat sheet

// Lessons

// Quiz questions

// Reading time

150 min

// Exam length

15 Q

// Coding exercises

1The Iterator ProtocolImplement __iter__ and __next__, handle StopIteration signals, and make custom objects iterable. 30 min 15 questions
2Generator Functions & yieldSuspend execution states, stream infinite sequences lazily, and delegate streams with yield from. 30 min 15 questions
3Custom Context ManagersGuarantee file and lock cleanup using the __enter__ and __exit__ protocol or contextlib decorators. 30 min 15 questions
4Itertools Stream CombinatorsCombine, slice, group, and cycle infinite or large data streams with zero memory duplication. 30 min 15 questions
5Type Hints & Static VerificationAnnotate function signatures, express union generics, and validate codebase correctness with mypy. 30 min 15 questions

Coding practice: write it yourself

Real Python, real checks: write your answer, press Run checks, and keep going until it passes. (4 exercises)

All module exercises

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Lab 1: Generator countdown

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Write a generator function down_to_zero(n) that yields numbers from n down to 0. Print: [3, 2, 1, 0].

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Lab 2: Header context manager

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Using @contextlib.contextmanager, create a manager bracket(name) that prints [{name}] before and [/{name}] after. Test with with bracket("AUDIT"): print("logged").

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Lab 3: Itertools cycle & islice

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Use itertools.cycle([1, 2]) and itertools.islice to take the first 5 elements. Print: [1, 2, 1, 2, 1].

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Lab 4: Annotate divider

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Define def divide(a: float, b: float) -> float: return a / b. Test with divide(10.0, 4.0) and print: Result: 2.5.

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References & Further Reading

Related entries from PyLabs's own reference library.

iter() (Return an iterator for a collection or other iterable.)
next() (Get the next item from an iterator.)