foo.rb

module NamedInitialize
  def initialize(*parameters)
    method(__method__).parameters.each do |type, k|
      next unless type == :key
      v = eval(k.to_s)
      next if v.nil?
      send("#{k}=", v) # Nope 
      instance_variable_set("@#{k}", v) # Nope
    end
  end
end

class Foo
  include NamedInitialize

  attr_accessor :bar, :baz, :biz

  def initialize(name, bar: nil, baz: nil, biz: nil)
    @name = name
    super
    puts self.baz
    
    # This works:
    # method(__method__).parameters.each do |type, k|
    #   next unless type == :key
    #   v = eval(k.to_s)
    #   instance_variable_set("@#{k}", v) unless v.nil?
    # end
  end
end

f = Foo.new("foo", baz: 42)