From: merch-redmine@...
Date: 2019-12-14T16:36:44+00:00
Subject: [ruby-core:96237] [Ruby master Bug#16421] public_send with empty keyword arguments (Ruby version < 2.7)

Issue #16421 has been updated by jeremyevans0 (Jeremy Evans).

Status changed from Open to Closed

You should use `ruby2_keywords`:

```ruby
  def delegate(name, *args, &block)
    public_send(name, *args, &block)
  end
  ruby2_keywords :delegate if respond_to?(:ruby2_keywords, true)
```

Then things will work correctly.  This type of code is the reason that `ruby2_keywords` was introduced.

----------------------------------------
Bug #16421: public_send with empty keyword arguments (Ruby version < 2.7)
https://bugs.ruby-lang.org/issues/16421#change-83129

* Author: zverok (Victor Shepelev)
* Status: Closed
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: 
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
Probably it is something that I've just missed, so it is more a question than bug report.
In Ruby < 2.7, I'd implement "delegate everything" method as such:
```ruby

def delegate(name, *args, &block)
  @something.public_send(name, *args, &block)
end
```
Now, while updating one of my gems to Ruby 2.7, I receive a warning (if SOME of the delegated methods accept keyword args):
```ruby
class A
  def simple_method(arg)
    p arg
  end

  def kwargs_method(arg, kwarg:)
    p [arg, kwarg]
  end

  def delegate(name, *args, &block)
    public_send(name, *args, &block)
  end
end

A.new.delegate(:kwargs_method, 1, kwarg: 2) # warning: The last argument is used as the keyword parameter
```
OK, that's understandable!
Now, I am trying to rewrite kode to work with both 2.6 and 2.7:
```ruby
class A
  def simple_method(arg)
    p arg
  end

  def kwargs_method(arg, kwarg:)
    p [arg, kwarg]
  end

  def delegate(name, *args, **kwargs, &block)
    public_send(name, *args, **kwargs, &block)
  end
end

A.new.delegate(:kwargs_method, 1, kwarg: 2)
A.new.delegate(:simple_method, 1)
```
It warks as expected under 2.7, but under 2.6, the last line throws:
```
tmp/delegate.rb:2:in `simple_method': wrong number of arguments (given 2, expected 1) (ArgumentError)
```

Is it something obvious that I am missing (I tried to search through the tracker, but can't detect related issues...). It there something I can do to have code working in both 2.6 and 2.7 without falling back to `ruby_2keywords` or `if RUBY_VERSION < '2.7'` (or checking for kwargs in `if method(name).parameters`)?..



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