possible object design for ascio's browser problem [WIP]

browser.rb

# Roughly based on my https://github.com/hxegon/aok_product/blob/e417b2bc6df9d772d09bb025e502c46a548d55e9/lib/extractor.rb
# This possibley has a bug in Browser, with @@actions being a class instance var. Might be fixable by changing @browsers to
# class inst var, and adding during #add_action instead of pushing it off too #initialize
class Implementations
  # Keeps track of what browsers are available, and what their actions are.
  # default is what get returned when nothing matches the action_list you give #for
  def initialize(actions=[], default:nil)
    # actions format: [(class_name, action_name)], good candidate for class extraction or just a struct
    @default = default
    actions.each { |(action_name, class_name| add_action(class_name, action_name) }
  end
  
  def add_action(class_name, action_name)
    implementations[class_name] << action_name
  end
  
  # Use this to search for an appropriate browser
  def find_for(action_list)
    implementations.each do |(klass, actions)|
      return klass if (action_list - actions).empty?
    end
    # this only runs if there's no implementation matching the action_list
    @default
  end
    
  private
  
  def implementations
    # Set because your actions are unique method names on a given class
    @implementations ||= Hash.new { |_, _| Set.new }
  end
end

class Browser
  @@browsers = Implementations.new
  
  class << self
    def def_action(name, &block)
      define_method(name.to_sym, block)
      @@browsers.add_action(class.name, name)
    end
  
    def def_synchr_action(name, &block)
      # Maybe change initialize to have a mutex parameter, def_action with the block in a Mutex#synchronize?
      raise NotImplementedError
    end
    
    def browsers
      @@browsers
    end
  end
end

class NilBrowser < Browser
  # probably a good idea?
  # Add sane standard nil actions?
end

browsers = Implementations.new(default: NilBrowser) # you could also make a DefaultBrowser