[ruby-core:103483] [Ruby master Feature#17808] Feature Request: JS like splat of Object properties as named method parameters

[jean.boussier@gmail.com]

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


Doesn't the implicit `to_hash` answer your demand?

```ruby
def foo(bar:)
  p bar
end

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

  def to_hash
    { bar: @bar }
  end
end

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

----------------------------------------
Feature #17808: Feature Request: JS like splat of Object properties as named method parameters
https://bugs.ruby-lang.org/issues/17808#change-91581

* 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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