[Python-ideas] Introduce collections.Reiterable

Steven D'Aprano steve at pearwood.info
Sat Sep 21 06:09:04 CEST 2013

On Sat, Sep 21, 2013 at 12:00:14AM -0400, Neil Girdhar wrote:
> If someone allows their class to fail the standardized test for
> Iterable/Reiterable/Sequence, that class doesn't deserve to be treated as
> one.  (Anyone can register their class as a subclass of the ABCs, or more
> simply inherit from one.)

This is Python, and duck-typing rules, not Java-like type checking. If 
you want a language with strict type checking designed by theorists, try 

The ultimate test in Python of whether something is iterable or not is 
to try iterating over it, and see if it succeeds or not. If it iterates 
like a duck, that's good enough to be treated as a duck.


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