[Python-Dev] Enum Eccentricities

Steven D'Aprano steve at pearwood.info
Mon Sep 23 17:16:23 CEST 2013

On Mon, Sep 23, 2013 at 07:53:00AM -0700, Guido van Rossum wrote:

> there is no rule that because you can
> access something on the class you should be able to access it on the
> instance. Try asking an instance for its class's __mro__ or __bases__.

It might not be a rule, but it's certainly the norm. I reckon that class 
attributes that aren't accessible from the instance are significantly 
more surprising than Color.red.blue.

I know I'm in a minority here, but Color.red.blue seems obvious and 
straightforward to me. The fact that it doesn't work surprises me. Given 

instance = Color.red
assert isinstance(instance, Color)  # well of course it is
assert hasattr(Color, "blue")

I would expect instance.blue to work, and I'm completely at a loss as to 
how Enum has managed to prevent it.


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