From: "marcandre (Marc-Andre Lafortune)" <ruby-core@...>
Date: 2013-03-11T10:22:00+09:00
Subject: [ruby-core:53299] [CommonRuby - Feature #7701] Non-optional (required) keyword args


Issue #7701 has been updated by marcandre (Marc-Andre Lafortune).


Method#parameter should return a different symbol for those, say :keyreq.

For arity, I opened #8072 regarding what I believe is a problem with the current behavior.

I would expect the arity of the following two methods to be equivalent:

    def new_way(req, named_req1:, named_req2:, named_opt: 42, **named_rest); end
    def old_way(req, options); end


----------------------------------------
Feature #7701: Non-optional (required) keyword args
https://bugs.ruby-lang.org/issues/7701#change-37479

Author: headius (Charles Nutter)
Status: Assigned
Priority: Normal
Assignee: nobu (Nobuyoshi Nakada)
Category: 
Target version: 


=begin
I would like to see keyword args expanded to include a non-optional form, to force callers to pass in keyword arguments.

Currently, we have required, optional, and rest positional args but only optional and rest keyword args. Consistency is one small reason to add required keyword args.

They would likely take the form of keyword with no default value:

  def foo(a:, b:)
    ...
  end

  foo(a: 1, b: 2) # ok
  foo(a: 1) # ArgumentError

Justifications:

* Consistency with positional args. A weak justification, I know.
* Avoiding a lot of boilerplate code by users wishing to enforce keywords being passed in. Example from tenderlove:

    def foo(a: raise('pass a'), b: raise('pass b'))

* Building a rich API atop keyword args would be easier (i.e. require fewer manual checks) if you could force some keywords to be passed in. Having to check everywhere when you require a keyword argument is unpleasant.
* Keyword args already enforces that no *additional* keyword args can be passed (without **), and it seems lopsided to have no way to enforce a minimum set of keyword args.
=end



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