iterator

id	behavioral/iterator
name	Iterator
aliases	cursor
guide_url	https://python-patterns.guide/gang-of-four/iterator/
problem	Traverse a container's elements without exposing how the container stores them.
symptoms	custom traversal order lazy sequence for loop over my own class stream elements one at a time
verdict	pythonic
caveats	The container and its iterator are different objects with different jobs: the container's __iter__ returns a fresh iterator; the iterator's __iter__ returns itself. Writing __next__ by hand is almost always the wrong level — a generator implements the whole protocol for you.
stdlib_sightings	iter next generators itertools

Iterator

Traverse elements without exposing storage — lazily when it matters. Verdict: pythonic — the pattern is the language; write generators.

Where	What
pattern/	The importable code: iterate_pages — chunked traversal behind one generator
docs/	Fundamentals · Implementation guide · External examples
examples/paginated_client/	Mini-project: observably lazy article API client built on pattern/
tests/	Behavioral tests for the pattern and the mini-project

uv run python -m patterns.behavioral.iterator.examples.paginated_client.main