From: kimmo.lehto@...
Date: 2019-08-22T12:01:33+00:00
Subject: [ruby-core:94480] [Ruby master Feature#16115] Keyword arguments from method calls or ignore extra hash keys in splat

Issue #16115 has been reported by kke (Kimmo Lehto).

----------------------------------------
Feature #16115: Keyword arguments from method calls or ignore extra hash keys in splat
https://bugs.ruby-lang.org/issues/16115

* Author: kke (Kimmo Lehto)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
Just a thought, feel free to insta-close as stupid.

Currently you can do this:

```
def hello(who:)
  puts "Hello, #{who}"
end

opts = { who: 'world' }
hello(who)
```

Or: 

```
def hello(who:, **_extra_opts) # without eating extra args, you get ArgumentError (unknown keyword: foo)
  puts "Hello, #{who}!"
end

hello(**{ who: 'world', foo: 'bar' })
```

Or even this:

```
def hello(_obj = nil, who: _obj&.who || raise(ArgumentError, "missing who:"))
  puts "Hello, #{who}!"
end

hello(OpenStruct.new(who: 'world'))
```

1) What if when you passed an object as an argument to a method that only accepts keyword arguments, the methods listed would be called? Then you could do:

```
require 'ostruct'
ostruct = OpenStruct.new(who: 'world, foo: 'bar')

def hello(who:)
  puts "Hello, #{who}!"
end

hello(ostruct)
```

2) Or perhaps add some sort of "triple splat" that would either a) do the method calling thing described above or b) do the regular hash splatting like `**` but ignore any keys present that are not listed as keyword arguments:

```
require 'ostruct'
ostruct = OpenStruct.new(who: 'world', foo: 'bar')

def hello(who:)
  puts "Hello, #{who}!"
end

# a:  
hello(***ostruct)  # would call ostruct.who to figure out `who:`

# or b: (currently with ** raises ArgumentError (unknown keyword: foo))
hello(***{ who: 'world', foo: 'bar' }) # would ignore any extra keys 
```

I think this could open up some possibilities (or a can of worms). 




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