ruby-core

Issue #10856 has been updated by mame (Yusuke Endoh).

Target version changed from 2.5 to 2.7
Status changed from Closed to Assigned

marcandre (Marc-Andre Lafortune) wrote:
> This is not actually fixed.
> 
> ```
> def foo
>   puts "OK"
> end
> 
> options = {}
> foo(**options) # => OK  (In 2.5.0preview1)
> args = []
> foo(*args, **options) # => ArgumentError: wrong number of arguments (given 1, expected 0)
> ```
> 
> The second call should also output "Ok".
> 
> Hopefully Nobu can crack this before 2.5.0

This is not completely fixed yet:

```
$ ruby -v
ruby 2.6.0p0 (2018-12-25 revision 66547) [x86_64-linux]
$ ruby -e 'def foo; end; options = {}; args = []; foo(*args, **options)'
$ ruby -e 'def foo(z); end; options = {}; args = []; foo(*args, 1, **options)'
Traceback (most recent call last):
    1: from -e:1:in `<main>'
-e:1:in `foo': wrong number of arguments (given 2, expected 1) (ArgumentError)
```

I go for the exception.  `opt = {}; foo(**option)` should consistently pass an empty hash instead of ignoring it.  It is not intuitive, but it IS the current spec of keyword argument.  This is a design flaw in the current spec.  I believe that it must be fixed by complete separation between keyword arguments and positional arguments (#14183).

----------------------------------------
Bug #10856: Splat with empty keyword args gives unexpected results
https://bugs.ruby-lang.org/issues/10856#change-77095

* Author: seantheprogrammer (Sean Griffin)
* Status: Assigned
* Priority: Normal
* Assignee: nobu (Nobuyoshi Nakada)
* Target version: 2.7
* ruby -v: ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin13]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN
----------------------------------------
When keyword args are passed to a method with splat, and there are no keyword args, an empty hash is sent. I would expect no argument to be given, same as splat with an empty array. For example:

```ruby
def foo
end

foo(**{})
```

This causes an argument error, as an empty hash is passed. I would expect the same behavior as

```ruby
def foo
end

foo(*[])
```



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