Ruby 3.4, No More TypeError With **nil As It Is Treated As An Empty Hash.

I'm a React, Javascript & Rails full-stack Software Engineer. I have been working remotely for the past two years in a remote village. Before joining as a Software Engineer I founded kwiq - a hyperlocal delivery startup to deliver things in remote villages.

In Ruby, the splat * and double splat ** operators are used for handling variable-length arguments in methods, especially when dealing with arrays and hashes.

The Single Splat operator (*) constructs and spreads out Arrays.

If we use it when defining a method, it constructs into an array.

def example_method ( * args ) puts "args are: #{ args } " end example_method ( 3 , 5 , 7 ) # => args are: [3, 5, 7]

If we use it when passing arguments as an array, it deconstructs the array into arguments.

def example_method ( a , b , c ) puts "args are: #{ a } , #{ b } , #{ c } " end example_method ( * [ 3 , 5 , 7 ]) # => args are: 3, 5, 7

The double Splat operator ( ** ) It works similarly. We can construct and spread out Hashes.

If we use it when defining a method, it constructs into an hash.

def example_method ( ** args ) puts "args are: #{ args } " end options = { x: 1 , y: 2 } example_method ( ** options ) # => args are: {:x=>1, :y=>2}

If we use it when passing arguments as an hash, it deconstructs the hash into arguments.

def example_method ( a :, b :, c :) puts "args are: #{ a } , #{ b } , #{ c } " end hash = { a: 1 , b: 2 , c: 3 } example_method ( ** hash ) # => args are: 1, 2, 3

Before

When we use the splat operator * and double splat operator ** with nil , they have specific behaviors.

When splat * operator used with nil , it essentially treats nil as an empty array.

def example_method ( * args ) puts "args are: #{ args } " end example_method ( * nil ) # => args are: []

When double splat ** operator used with nil , it raises an error because nil cannot be implicitly converted into a hash.

def example_method ( ** args ) puts "args are: #{ args } " end example_method ( ** nil ) # => no implicit conversion of nil into Hash (TypeError)

After

Ruby 3.4 fixes this inconsistent behavior between array splat *nil and hash splat **nil with this PR by not raising any error with **nil .

When **nil is used, it is treated similarly to **{} , which passes no keywords and does not call any conversion methods.