[ruby-core:103488] [Ruby master Feature#17808] Feature Request: JS like splat of Object properties as named method parameters

Issue #17808 has been updated by byroot (Jean Boussier).


> Is there a way to modify existing declared methods adding that parameter

Well, I suppose you can decorate the methods and filter the extra keywords, a bit tricky but doable:

```ruby
class Module
  def ignore_extra_parameters(method_name)
    method = instance_method(method_name)
    keyword_args = method.parameters.filter_map { |type, name| name if type == :key || type == :keyreq }
    define_method(method_name) do |*args, **kwargs, &block|
      method.bind_call(self, *args, **kwargs.slice(*keyword_args), &block)
    end
  end
end

class MyObject
  def initialize(bar)
    @bar = bar
  end

  def to_hash
    { bar: @bar, plop: 42 }
  end
end

module Test
  extend self
  ignore_extra_parameters def foo(bar:)
    p bar
  end
end

Test.foo(**MyObject.new(42)) # => 42
```


But ultimately your whole feature request rely on a very specific JS "feature" (many people would call it a cruft), that extra arguments are simply ignored.

That's not the case in Ruby, every argument must be accounted for. And while I'm merely an observer of the ruby-core development, I'm pretty sure it isn't acceptable to change. So I doubt there any way such feature would be implemented.

Or you'd need to introduce some new syntax for the caller to specify that the extra parameters should be discarded, but again, not very likely to happen.





----------------------------------------
Feature #17808: Feature Request: JS like splat of Object properties as named method parameters
https://bugs.ruby-lang.org/issues/17808#change-91586

* Author: Lithium (Brad Krane)
* Status: Open
* Priority: Normal
----------------------------------------
I'm pretty sure there is no equivalent Ruby for a very convenient JS way to enter named function parameters as below:

``` javascript
const test = ({param1,
 param2,
 param3 = null,
 param4 = false,
 param5 = null,
 }={}) => {
   console.log(`${param1}, ${param2}, ${param3}, ${param4}, ${param5}\n`)    
 }
let obj = {
 param1: 23,
 param2: 234,
 param3: 235,
 param4: 257
};

test({...obj});

```

which is super convenient and as far as I'm aware there is no standard Ruby equivalent. It can be accomplished in Ruby but the call syntax is far less nice. A couple examples below:

``` ruby
# Implementing such a feature wouldn't be too difficult.
# Ok so here is what you could do it. Patch Kernel with a method splat. (Sorry in advance for formatting)
module Kernel
  def splat obj, method:
    new_hash = method.parameters.reduce({}) do |hash, attrr|
      hash[attrr.last] = obj.send(attrr.last)
      hash
    end
  end
end

# Then you can pass it a list of symbols.
# Then for your method:
def some_method name:, weight: 
    puts "#{name} weighs #{weight}"
end

class Dog
  attr_reader :name, :weight
  def initialize name:,weight: 
    @name = name
    @weight = weight
  end
end

a_dog = Dog.new( name: 'fido', weight: '7kg')
hash_puppy = a_dog.splat(a_dog, method: method(:some_method)  )

some_method(**hash_puppy)
```


or what I think is a bit better:

``` ruby
# Same class as above
a_dog = Dog.new( name: 'fido', weight: '7kg')

def other_splat  obj, method:
  new_hash = method.parameters.reduce({}) do |hash, attrr|
    if obj.class <= Hash
      hash[attrr.last] = obj[attrr.last]      
    else
      hash[attrr.last] = obj.send attrr.last
    end
    hash
  end
  method.call **new_hash
end

other_splat(a_dog, method: method(:some_method))

# above line should be like:
# some_method ...a_dog

```

Source: https://gist.github.com/bradkrane/e051d205024a5313cb4a5b9eb1eae0e3

I'm sure I'm missing a possibly more clever way to accomplish this, but I'm pretty sure something like `other_splat(a_dog, method: method(:some_method))` is about as close as it can get, unless I'm missing something? It would be quite nice to have a similar syntax as JS but in Ruby: `some_method ...a_dog`

Thanks for your time and attention!



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