[Python-Dev] Keyword-only parameters

Larry Hastings larry at hastings.org
Tue Apr 14 21:40:32 CEST 2015



On 04/14/2015 01:40 PM, Eric V. Smith wrote:
> I'm working on adding a numeric_owner parameter to some tarfile methods
> (http://bugs.python.org/issue23193),
>
> In a review, Berker suggested making the parameter keyword-only. I agree
> that you'd likely never want to pass just "True", but that
> "numeric_owner=True" would be a better usage.

Boolean parameters are the classic problem that keyword-only parameters 
solve.  It forces the caller to provide context for the parameter, 
solving the mystery-meat API problem of

    tarfile.extractall(".", None, True)



On 04/14/2015 01:56 PM, Paul Sokolovsky wrote:
> But newer parts of stdlib, e.g. asyncio, visibly overuse kw-only args.

Overuse?  asyncio?  You mean "that thing Guido just wrote last year"?  
The most practical definition I've heard for the word "pythonic" is 
"code like Guido writes".


//arry/
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