plugins system: nested

base.rb

# ./base.rb

require 'base/plugins'

module Base
  class Server
    include Plugins

    def say(what)
      p "say: #{what}"
      @config = "default"
    end
  end
end

s = Base::Server.new

puts s.instance_eval("class << self; self; end").ancestors
puts
s.say("hello world")
puts

s.activate "something"

puts s.instance_eval("class << self; self; end").ancestors
puts
s.say("hello world")
puts

output

$ tree
.
|-- base
|   |-- plugins
|   |   `-- something.rb
|   `-- plugins.rb
`-- base.rb

$ ruby base.rb
Base::Server
Base::Plugins
Object
Kernel

"say: hello world"

Base::Server
Base::Plugins
Object
Kernel

"say: hello world"

plugins.rb

# ./base/plugins.rb

module Base
  module Plugins
    def plugins
      @plugins ||= []
    end

    def activate plugin
      require 'base/plugins/' + plugin
      plugins << plugin
      plugin = Base::Plugins.const_get(plugin.capitalize)
      plugin.activate if plugin.respond_to?(:activate)
    end
  end
end

something.rb

# ./base/plugins/something.rb

module Base
  module Plugins
    module Something
      def self.activate
        Base::Server.send :extend, Redefinitions
      end

      module Redefinitions
        def process(document)
          p "Under control of Something:"
          super
        end
      end
    end
  end
end