Dynamic Entities

camera.json

{
  "name": "Camera",
  "components": [
    {
      "name": "Position",
      "attributes": [
        { "x": 100 }
      ]
    }
  ]
}

entities.rb

module Component

end

module System
  module World
    class << self
      def load args
        args.state.entities = []

        fn.each $gtk.list_files('data/components') do |component_def|
          new_component_module $gtk.parse_json_file "data/components/#{component_def}"
        end

        fn.each $gtk.list_files('data/entities') do |entity_def|
          new_entity_class $gtk.parse_json_file "data/entities/#{entity_def}"
        end
      end

      def new_component_module component_def
        Component.const_set(component_def['name'], Module.new do
          if component_def['attributes']
            fn.each component_def['attributes'] do |attribute|
              send :attr_accessor, attribute.keys[0].to_sym
              send :instance_variable_set, :"@#{attribute.keys[0]}", attribute.values[0]
            end
          end

          if component_def['behaviors']
            fn.each component_def['behaviors'] do |behavior|
              send :include, Component.const_get(behavior)
            end
          end

          def self.included klass
            fn.each instance_variables do |var|
              klass.instance_variable_set var, (instance_variable_get var)
            end
          end
        end)
      end

      def new_entity_class entity_def
        Object.const_set(entity_def['name'], Class.new do
          if entity_def['components']
            fn.each entity_def['components'] do |component|
              send :include, Component.const_get(component['name'])

              if component['attributes']
                fn.each component['attributes'] do |attribute|
                  send :instance_variable_set, :"@#{attribute.keys[0]}", attribute.values[0]
                end
              end
            end
          end

          def self.new(...)
            object = allocate
            object.send(:initialize, ...)
            fn.each instance_variables do |var|
              object.instance_variable_set var, (instance_variable_get var)
            end

            object
          end
        end)
      end
    end
  end
end

position.json

{
  "name": "Position",
  "attributes": [
    { "x":  0 },
    { "y":  0 },
    { "z" : 0 }
  ]
}