ruby_constructor_args.rb

class Foo
  def meth(a:, b:, c:)
    method(__method__).parameters.map(&:last).each do |var|
      instance_variable_set("@#{var}", binding.local_variable_get(var))
    end
  end
  def inspect
   puts "@a = #{@a}"
   puts "@b = #{@b}"
   puts "@c = #{@c}"
  end
end

inst = Foo.new
inst.meth(a: 'a', b: 'b', c: 'c')
inst.inspect