Objects and classes

A class is how you give a value its own behaviour — so that adding two amounts of money checks the currency, and comparing them compares what they mean rather than where they live in memory. These exercises are about the handful of dunder methods that make an object feel like part of the language instead of a bag of attributes.

10 exercisesdifficulty 2–4~240 min in total

—Exercises 10 exercises

The class you barely have to write @dataclass, generated __eq__ and __repr__ ~18 min A Stack that knows how long it is __len__ and free truthiness, private attributes ~20 min Settings nobody can change behind your back frozen dataclass, hashable values ~22 min Keys that do not care about capitals __getitem__ and friends, normalising at the boundary ~24 min Stock that cannot go negative methods that guard state, zero is not a stock level ~24 min A Money value that behaves like one __eq__ and NotImplemented, __add__ ~25 min A Temperature that cannot be impossible @property, computed attributes ~25 min An object you can loop over twice __iter__, iterable versus iterator ~24 min A set that keeps the order you added things operator dunders, returning new objects ~28 min Versions that sort like versions tuple comparison, functools.total_ordering ~30 min