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

Michael Foord fuzzyman at voidspace.org.uk
Fri Aug 16 10:01:51 CEST 2013

On 16 Aug 2013, at 02:30, R. David Murray <rdmurray at bitdance.com> wrote:

On Thu, 15 Aug 2013 23:28:39 +0300, Michael Foord <fuzzyman at voidspace.org.uk> wrote:

On 15 Aug 2013, at 21:10, "Eric V. Smith" <eric at trueblade.com> wrote:

On 08/15/2013 01:58 PM, Mark Dickinson wrote: On Thu, Aug 15, 2013 at 2:08 PM, Steven D'Aprano <steve at pearwood.info_ _<mailto:steve at pearwood.info>> wrote:

- Each scheme ended up needing to be a separate function, for ease of both implementation and testing. So I had four private median functions, which I put inside a class to act as namespace and avoid polluting the main namespace. Then I needed a "master function" to select which of the methods should be called, with all the additional testing and documentation that entailed. That's just an implementation issue, though, and sounds like a minor inconvenience to the implementor rather than anything serious; I don't think that that should dictate the API that's used. - The API doesn't really feel very Pythonic to me. For example, we write: And I guess this is subjective: conversely, the API you're proposing doesn't feel Pythonic to me. :-) I'd like the hear the opinion of other python-dev readers. I agree with Mark: the proposed median, median.low, etc., doesn't feel right. Is there any example of doing this in the stdlib? I suggest just median(), medianlow(), etc. If we do end up keeping it, simpler than the callable singleton is: def median(): return 'median' ... def medianlow(): return 'median.low' ... median.low = medianlow del medianlow median() 'median' median.low() 'median.low' There's the patch decorator in unittest.mock which provides: patch(...) patch.object(...) patch.dict(...) The implementation is exactly as you suggest. (e.g. patch.object = patchobject) Truthfully there are a number of things about the mock API that make me uncomfortable, including that one. But despite that I'm glad we didn't try to re-engineer it. Take that as you will :)

Hah. mock used to provide separate patch and patch_object "functions" (they're really just factory functions for classes) but "patch.object" and "patch.dict" are easy to remember and you only have to import a single object instead of a proliferation. In my experience it's been a better API. The separate function was deprecated and removed a while ago.

Other parts of the mock API and architecture are somewhat legacy - it's a six year old project with a lot of users, so it's somewhat inevitable. If starting from scratch I wouldn't do it very differently though.

Michael

--David

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