[ruby-core:88805] [Ruby trunk Feature#15049] [Request] Easily access all keyword arguments within a method

Issue #15049 has been updated by zverok (Victor Shepelev).


@duerst

> Maybe I'm totally confused, but what's wrong with using `**keyword_arguments`?

I am not the ticket's authors, but I understand the demand and met with the same requirement in some real-life projects. The most expressive example would be something like this:

```ruby
def get(path:, accept: :json, headers: {}, **options)
  _request(method: :get, __all the rest of what have passed to this method___)
end

def post(path:, body:, accept: :json, headers: {}, **options)
  _request(method: :post, __all the rest of what have passed to this method___)
end
# ...and so on
```

Two of currently available options:
1. Accept just `**arguments`, and make checking what was mandatory, what should have default value and so on manually (also making auto-generated docs less expressive)
2. Accept everything as in my example, and then just do

```
_request(method: :get, path: path, body: body, accept: accept, headers: headers, **options)
```
...that looks not DRY at all.

So...

----------------------------------------
Feature #15049: [Request] Easily access all keyword arguments within a method
https://bugs.ruby-lang.org/issues/15049#change-73845

* Author: bherms (Bradley Herman)
* Status: Feedback
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
As a developer, I'd like to leverage the power of keyword arguments (requirements, defaults, etc) and then be able to access a hash of all the arguments supplied.

~~~ ruby
def foo(bar:, baz: 1, qux: 2...)
  post('/', body: kargs)
end
~~~

This is currently possible by leveraging the RubyVM debug inspector and some meta programming to retrieve the binding and name of the calling method.  There is a gem https://github.com/banister/binding_of_caller that abstracts away the logic of crawling through the frame bindings in the debug inspector to find the binding of the caller, but I feel like this functionality would be useful in Ruby.

With the binding_of_caller gem, you can hack together a kargs method like so:

~~~ ruby
def kargs
  method(caller_locations(1,1)[0].label).parameters.map do |(_type, name)|
    [name, binding.of_caller(2).local_variable_get(name)]
  end.to_h
end
~~~

This gets the name of the calling method, pulls the local variables from the method, retrieves the binding, and then retrieves the variables from the binding.  By exposing a simpler API to retrieve the caller binding, a `kargs` method could be added to Ruby fairly easily I would think.





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