Functions in Depth

Scope rules, closures and iterators — how functions really work.

Easy

Functions are objects: they can be stored, passed and returned. Understanding scope and closures explains decorators and many library APIs.

Sub-topics (3)

Names are looked up in Local, Enclosing, Global, then Built-in scope.

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A nested function that remembers variables from the function that created it.

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Any object with __iter__ and __next__ can be looped over; next() raises StopIteration at the end.

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