ruby_splat_issue.rb

# An example to illustrate a problem with splat operator when using different Ruby versions

# When run under Ruby 2.1.5 the output is:
#
# Passing in arguments:
#  access_control: 123
#  (splat array): [:type, #<ToHashableClass:0x007fbf1c85d4b8 @hash={1=>2, 3=>4}>]
#
# ToHashableClass#to_hash method called
#
# Received arguments:
#  access_control: 123
#  type: :type
#  resource: #<ToHashableClass:0x007fbf1c85d4b8 @hash={1=>2, 3=>4}>
#  status: 200
#  meta_data: {}

# When running under Ruby 2.3.0 the output is:
#
# Passing in arguments:
#  access_control: 123
#  (splat array): [:type, #<ToHashableClass:0x007fa7bb0cc898 @hash={1=>2, 3=>4}>]
#
# ToHashableClass#to_hash method called
#
# Received arguments:
#  access_control: 123
#  type: :type
#  resource: {1=>2, 3=>4}
#  status: 200
#  meta_data: {}

class SomeClass
  def initialize(access_control, type, resource = [], status: 200, **meta_data)
    puts "Received arguments:"
    printf " access_control: "; p access_control
    printf " type: "; p type
    printf " resource: "; p resource
    printf " status: "; p status
    printf " meta_data: "; p meta_data
  end
end

class ToHashableClass
  def initialize
    @hash = { 1 => 2, 3 => 4}
  end

  def to_hash
    puts "ToHashableClass#to_hash method called"
    puts ""
    @hash
  end
end

def create_with_splat(*args)
  access_control = 123

  puts "Passing in arguments:"
  printf " access_control: "; p access_control
  printf " (splat array): "; p args
  puts ""

  SomeClass.new(access_control, *args)
end

type = :type
resource = ToHashableClass.new
create_with_splat(type, resource)