[Python-Dev] enum discussion: can someone please summarize open issues? (original) (raw)

Guido van Rossum guido at python.org
Fri May 3 16:46:04 CEST 2013

On Fri, May 3, 2013 at 7:14 AM, Eli Bendersky <eliben at gmail.com> wrote:

I'm just curious what it is about enums that sets everyone on a "let's make things safer" path. Python is about duck typing, it's absolutely "unsafe" in the static typing sense, in the most fundamental ways imaginable. When programmatically invoking a method on a class (say some sort of RPC), we don't check that the class is of the correct type. We invoke a method, and if it quacks, that's a good enough duck. If it was actually the wrong class, something will break later. EAFP Is a central Python tenet, whether we like it or not. If one looks for static guarantees, Python surely shouldn't be the preferred language, no?

And concretely, how is this case different from any programmatic attribute access in Python objects? You can pass dunders to getattr() and it probably wasn't what you meant, but Python does not do this type checking for you. Why is an Enum different than any other class?

Let's make that a topic for a separate, more philosophical thread, python-ideas.

Back to this particular issue, I haven't seen code in the style that Greg proposes in decades, and I don't think it is an important enough use case to support more directly than through getattr() + isinstance().

-- --Guido van Rossum (python.org/~guido)

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