[Python-Dev] itertools predicates (original) (raw)

Francisco Couzo franciscouzo at gmail.com
Fri Nov 4 15:35:17 EDT 2016

Well sorry about it, I didn't know about that PEP 8 line, disregard this thread then :)

On Fri, Nov 4, 2016 at 2:29 PM, Raymond Hettinger < raymond.hettinger at gmail.com> wrote:

> On Nov 3, 2016, at 3:51 PM, Steven D'Aprano <steve at pearwood.info> wrote: > > Before there can be a solution, there first has to be a problem that > needs solving. "Lack of consistency" is not necessarily a problem. The > intertools functions are quite different, they do different things with > different APIs. The question here should not be "why don't these > functions take None as an argument?", rather it should be "why should > these functions take None as an argument?". I concur with Steven who articulated the issue perfectly. There isn't an actual problem here that needs to be solved (i.e. not a single user report in 15 years indicating that the API wasn't meeting the needs for real use-cases). I'm disinclined to churn the API unless there is a real need. FWIW, groupby() has the predicate as an optional argument so that you can write groupby('aaabbc') and have it group by value (much like the key-function on sorted() is optional). The two filter variants allow None as the first argument only for historical reasons -- once "bool" came along, it would have been better to write filter(bool, someiterable) in preference to using None which is less clear about its intention. The takewhile/dropwhile tools didn't have the same constraint to match a historical API, so there was an opportunity to have a clearer API with a simpler signature. As Terry suggested, if you have other itertools feature requests, please put them on the tracker an assign them to me. Thank you,

Raymond

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