__next__
__next__ is a Python special method that returns an iterator’s next item or raises StopIteration when no items remain.
Python Workout: 50 ten-minute exercises
__next__ is a Python special method that returns an iterator's next value and signals exhaustion when no values remain.
- How it is used
- Uses __next__ to implement custom iteration and explain how for loops obtain values.
- How deep it goes
- Explains state, advancement, exhaustion, and reusable iterator designs, while deferring broader iterator variations to exercises.
- Examples
- Demonstrates LoudIterator, MyEnumerate, Circle, generator expressions, and generator functions.
- What you can do after
- Builds custom iterators that return values, maintain position, and signal exhaustion with StopIteration.
Read how Python Workout: 50 ten-minute exercises explains __next__ →
Python Workout, Second Edition
The __next__ method is Python's special method that returns the next value from an iterator or raises StopIteration when no values remain.
- How it is used
- Implements the value-by-value production step underlying Python for loops and direct next() calls.
- How deep it goes
- Explains state storage, boundary checks, returned values, StopIteration, and separate iterator objects, but defers generator internals.
- Examples
- Demonstrates LoudIterator, MyEnumerate, Circle, generator expressions, and a custom range-like iterator.
- What you can do after
- Builds a class-based iterator that tracks progress, returns values, and terminates correctly with StopIteration.
Related concepts
- iteratorpart of · An iterator is an object or abstraction that provides successive values from a sequence or data source through a traversal protocol.
- StopIterationproduces · StopIteration is the Python exception raised when an iterator or generator has no further values to produce.
- nextused by · An iterator operation that advances an iterator and returns its next value or result, with behavior on exhaustion determined by the API.
- generatorused by · A generator is a language construct or computation that produces values incrementally on demand, typically suspending and resuming while preserving its state.
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