Fredrik Lundh wrote: >> And again, why would you *make* me, the user-programmer, type >> >> make_person(name=namex, age=agex, phone=phonex, location = locationx) >> #instead of >> make_person(namex,agex,phonex,locationx) >> ? > > because a good API designer needs to consider more than just the current > release.
I believe that it's quite possible that you're right, but I think more concrete answers would be helpful. I.e., how does having parameters that are syntactically keyword-only (as opposed to being simply documented as keyword-only) help you develop an API over time? I gave some thought to it, and can come up with a few answers. In all cases, assume a user BadUser, who decided to use positional arguments for arguments that you documented as keyword-only. - You would like to deprecate, and eventually remove, an argument to a function. For people who read your documentation, and use keyword args for the keyword-only arguments, their code will break in a clean, easy-to-understand way. But BadUser's code may break in strange hard-to-understand ways, since their positional arguments will get mapped to the wrong function arguments. - You would like to add a new parameter to a function, and would like to make that new parameter available for positional argument use. So you'd like to add it before all the keyword arguments. But this will break BadUser's code. - You have a function that takes one argument and a bunch of keyword options, and would like to change it to accept *varargs instead of just one argument. But this will break BadUser's code. I think that this kind of *concrete* use-case provides a better justification for the feature than just saying "it will help API design." As someone who has had a fair amount of experience designing & maintaining APIs over time, perhaps you'd care to contribute some more use cases where you think having syntactically keyword-only arguments would help? -Edward _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
