From: "zverok (Victor Shepelev) via ruby-core" <ruby-core@...>
Date: 2023-01-30T21:41:11+00:00
Subject: [ruby-core:112123] [Ruby master Feature#19370] Anonymous parameters for blocks?

Issue #19370 has been updated by zverok (Victor Shepelev).


Note that it might lead to very confusing behavior when the surrounding method does have anonymous arguments:

```ruby
def test(*)
  # ...

  proc { |*| p(*) }.call(1)
end

test(2) #=> prints 2 (method's anonymous arguments, not proc's)
```

Note that code is valid, and sanely looking syntax, which is very easy to (mis)interpret: it is "obvious" from the first sight that proc uses its anonymous args. 

The resulting behavior might be very confusing (especially in complicated code, long methods, and subtle differences in data).



----------------------------------------
Feature #19370: Anonymous parameters for blocks?
https://bugs.ruby-lang.org/issues/19370#change-101559

* Author: zverok (Victor Shepelev)
* Status: Assigned
* Priority: Normal
* Assignee: matz (Yukihiro Matsumoto)
----------------------------------------
Just to clarify: are anonymous parameters delegation is planned to support in blocks? 

It would be a nice addition, if it is possible to implement:
```ruby
# data in form [request method, URL, params]:
[
  [:get, 'https://google.com', {q: 'Ruby'}, {'User-Argent': 'Google-Chrome'}],
  [:post, 'https://gist.github.com', 'body'],
  # ...
].each { |method, *| request(method.to_s.upcase, *) }
```
...and at the very least, consistent with what the method definition can have.

If they are NOT planned to be implemented, I believe that at least error messages should be made much clearer, because currently, this would happen while running the code above:
> no anonymous rest parameter (SyntaxError)

I understand the reason (the `request` clause doesn't "see" anonymous parameter of the **block**, and claims that current **method** doesn't have them), but it looks honestly confusing and inconsistent.



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