[Python-Dev] PEP 450 adding statistics module (original) (raw)

Eric V. Smith eric at trueblade.com
Fri Aug 16 05:40:45 CEST 2013

On 8/15/2013 10:44 PM, Steven D'Aprano wrote:

On 16/08/13 04:10, Eric V. Smith wrote:

I agree with Mark: the proposed median, median.low, etc., doesn't feel right. Is there any example of doing this in the stdlib? The most obvious case is datetime: we have datetime(), and datetime.now(), datetime.today(), and datetime.strftime(). The only API difference between it and median is that datetime is a type and median is not, but that's a difference that makes no difference: both are callables, and being a type is an implementation detail. dict used to be a function that returned a type. Now it is a type. Implementation detail. Even builtins do this: dict() and dict.fromkeys(), for example.

Except those classmethods are all alternate constructors for the class of which they're members (it's datetime.strptime, not .strftime). That's a not uncommon idiom. To me, that's a logical difference from the proposed median.

I understand it's all just namespaces and callables, but I think the proposed median(), median.low(), etc. just confuse users and makes things less discoverable. I'd expect dir(statistics) to tell me all of the available functions in the module. I wouldn't expect to need to look inside all of the returned functions to see what other functions exist.

To see what I mean, look at help(itertools), and see how much harder it is to find chain.from_iterable than it is to find combination_with_replacement.

BTW, I'm +1 on adding the statistics module.

-- Eric.

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