color

module Gosu
  class Color
    # Setting up for YAML
    YAML_DOMAIN = 'libgosu.org,2010'
    YAML_TYPE = 'color'

    YAML::add_domain_type(YAML_DOMAIN, YAML_TYPE) do |type, value|
      p type, value
      Gosu::Color.new(*value[:rgba])
    end

    def to_yaml
      "--- #{to_yaml_type} \nrgba: [#{red}, #{green}, #{blue}, #{alpha}]\n"
    end

    def to_yaml_type
      "!#{YAML_DOMAIN}/#{YAML_TYPE}"
    end
  end
end

Gosu::Color.new(1, 2, 3, 4).to_yaml
YAML.load(Gosu::Color.new(1, 2, 3, 4).to_yaml)

color_yaml.rb

module Gosu
  class Color
    def to_yaml
      "--- !ruby/object:Gosu::Color\nred:#{red}\nblue:#{blue}\ngreen:#{green}\nalpha:#{alpha}\n"
    end
  end
end

module Gosu
  class Color
    def to_yaml
      "--- !ruby/object:Gosu::Color\ncolor:[#{red},#{green},#{blue},#{alpha}]\n"
    end
  end
end

Gosu::Color.new(1, 2, 3, 4).to_yaml
#=> "--- !ruby/object:Gosu::Color\nred:2\nblue:4\ngreen:3\nalpha:1\n"

YAML.load(Gosu::Color.new(1, 2, 3, 4).to_yaml)

gistfile3.txt

module Gosu
  class Color
    # Json serialization.
    public
    def to_json
      {
        'json_class' => self.class.name,
        'rgba' => [red, green, blue, alpha]
      }.to_json
    end

    public
    def self.json_create(attributes)
      new(*attributes['rgba'])
    end
 end
end

Gosu::Color.new(1, 2, 3, 4).to_json
JSON.parse(Gosu::Color.new(1, 2, 3, 4).to_json)