From: "jeremyevans0 (Jeremy Evans) via ruby-core" <ruby-core@...>
Date: 2024-05-24T21:31:43+00:00
Subject: [ruby-core:118011] [Ruby master Feature#20508] Explicit access to *, **, &, and ...

Issue #20508 has been updated by jeremyevans0 (Jeremy Evans).


Implementing this would require removing recent and planned optimizations to avoid allocations that take advantage of the fact that `*` and `**` are not directly accessible as objects, only passable as splats.

> I'm not sure how to access the `&` variable, unless I name it. The same applies to endless ruby methods.

You can already do this for the block argument:

```
block_argument = ->(&b){b}.(&)
```

For the `*` and `**` arguments, you cannot get direct access to them, but you can easily make copies of them.  If you want all of `*`, `**`, and `&`:

```
arguments, keyword_arguments, block_argument = ->(*a, **kw, &b){[a, kw, b]}.(*, **, &);
```

----------------------------------------
Feature #20508: Explicit access to *, **, &, and ...
https://bugs.ruby-lang.org/issues/20508#change-108431

* Author: bradgessler (Brad Gessler)
* Status: Open
----------------------------------------
I find debugging and certain meta-programming tasks challenging because there's no explicit APIs for accessing certain types of arguments in Ruby.

Here's some example code:

```ruby
def splats(one, *, two: nil, **, &)
  # These work
  p(*)
  p(**)
  # But the block doesn't show a proc.
  p(&)

  # This would show [:one, :two, :_]
  p binding.local_variables
end

splats(:arg, two: true) do
  42
end
```

I'm not sure how to access the `&` variable, unless I name it. The same applies to endless ruby methods.

I'd like to see a way to explicitly call bindings for those methods. Something like this (not sure if binding is the right place for it):

```ruby
def splats(one, *, true: nil, **, &)
  binding.arguments # Returns an array
  binding.keyword_arguments # Returns a hash
  binding.block_argument # Returns a block
end
```

These methods would give me access to the values used to call the method.




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