[Python-ideas] Keyword-only arguments?

[Amber Yust]

Interesting. I don't think I've ever seen it used, even having looked at
Python 3 code. For those who have worked with more Python 3 code than I
have, do you ever see it used?

On Wed, Jun 17, 2015 at 12:02 PM Chris Kaynor <ckaynor at zindagigames.com>
wrote:

> On Wed, Jun 17, 2015 at 11:58 AM, Amber Yust <amber.yust at gmail.com> wrote:
>
>> One thing that has been a source of bugs and frustration in the past is
>> the inability to designate a named keyword argument that cannot be passed
>> as a positional argument (short of **kwargs and then keying into the dict
>> directly). Has there been any previous discussion on the possibility of a
>> means to designate named arguments as explicitly non-positional?
>>
>> Not a solid proposal, but to capture the essential difference of what I'm
>> thinking of, along the lines of...
>>
>>     def foo(bar, baz=None, qux: None):
>>
>> where bar is a required positional argument, baz is an optional argument
>> that can have a value passed positionally or by name, and qux is an
>> optional argument that must always be passed by keyword.
>>
>> Such a means would help avoid cases where a misremembered function
>> signature results in a subtle and likely unnoticed bug due to unintended
>> parameter/argument mismatch.
>>
>> (It's possible that this has been discussed before - a cursory search of
>> python-ideas didn't bring up any direct discussion, but I may have missed
>> something. If you have a link to prior discussion, please by all means
>> point me at it!)
>>
>
> This feature was added to Python 3 about 9 years ago, see
> https://www.python.org/dev/peps/pep-3102/. A quick search for "python
> keyword only arguments" on Google found it.
>
> Guido's time machine strikes again!
>
> Chris
>
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