[Python-ideas] constant/enum type in stdlib

[Barry Warsaw]

I'll agree that enums are subject to personal taste, and I am opinionated
about the syntax and semantics, as should be evident in my library :).

On Jan 30, 2013, at 09:13 PM, Giampaolo Rodolà wrote:

>1) a const/enum type looks like something which is subject to personal
>taste to me. I personally don't like, for example, how flufl requires
>to define constants by using a class.

In practice, I find this quite nice.  In my larger projects, I define the
enum class an the interface module and often intersperse comments among the
enum values so that more documentation is provided to the reader.

>It's just a matter of taste but to me module.FOO looks more "right"
>than module.Bar.FOO.

I almost always 'from module import MyEnum' so typical use looks something
like:

    if thing.color is Color.red:
        ...
    elif thing.color is Color.blue:
        ...

Again, in practice, I find it quite readable and just the right level of
verbosity.

>Also "Colors.red < Colors.blue" raising an exception is something
>subject to personal taste.

I guess, if you like blue more than red, but what if you like red more than
blue? :)

Ordered enums just don't usually make sense, and if they really did, you can
coerce to int to do the comparison (but again, I've never needed it, so YAGNI).

>2) introducing something like that (class-based) wouldn't help
>migrating the existent module-level constants we have in the stdlib.
>Only new projects or new stdlib modules would benefit from it.

Sure, but I don't think this is necessarily about converting the stdlib.  We
rarely do such mass conversions anyway.

>3) other than being subject to personal taste, a const/enum type is
>also pretty easy to implement.

True, depending on the semantics, syntax, and feature you want.

>4) I'm getting the impression that the language is growing too big. To
>me, this looks like yet another thing that infrequent users have to
>learn before being able to read and understand Python code.
>Also consider that people lived without const/enum for 2 decades now.

Well, I would agree that the *language* doesn't need them, but that's
different than the stdlib.  Maybe the stdlib still doesn't need them either.
I don't personally care either way except to save me the trouble of writing up
another PEP. :)

As for the language growing too big, maybe Pycon 2013 is time for another one
of Guido's infamous polls!

Cheers,
-Barry
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