Named Parameters in Ruby Structs

Question

I\'m pretty new to Ruby so apologies if this is an obvious question.

I\'d like to use named parameters when instantiating a Struct, i.e. be able to specify which ite

Answer 1

A solution that only allows Ruby keyword arguments (Ruby >=2.0).

class KeywordStruct < Struct
  def initialize(**kwargs)
    super(kwargs.keys)
    kwargs.each { |k, v| self[k] = v }
  end
end

Usage:

class Foo < KeywordStruct.new(:bar, :baz, :qux)
end


foo = Foo.new(bar: 123, baz: true)
foo.bar  # --> 123
foo.baz  # --> true
foo.qux  # --> nil
foo.fake # --> NoMethodError

This kind of structure can be really useful as a value object especially if you like more strict method accessors which will actually error instead of returning nil (a la OpenStruct).