Better plugin registration

lib/awesome_print/ext/example.rb

@@ -14,3 +14,5 @@ module AwesomePrint
     end
   end
 end
+
+AwesomePrint::Plugin.register(AwesomePrint::Radix)

lib/awesome_print/plugin.rb

@@ -4,8 +4,12 @@
 # See LICENSE file or http://www.opensource.org/licenses/mit-license.php
 #------------------------------------------------------------------------------
 module AwesomePrint
-  class Plugin
-    def self.add(mod)
+  module Plugin
+    extend self
+
+    @list = []; attr_reader :list
+
+    def add(mod)
       formatter = AwesomePrint::Formatter
       formatter.send(:include, mod)
 
@@ -13,5 +17,40 @@ module AwesomePrint
       formatter.send(:alias_method, :"cast_without_#{hook}", :cast)
       formatter.send(:alias_method, :cast, :"cast_with_#{hook}")
     end
+
+    def register(mod)
+      puts "mod.instance_methods: #{mod.instance_methods}"
+      unless mod.instance_methods.include?(:cast)
+        raise RuntimeError, "#{mod} plugin should define cast(object, type) instance method"
+      end
+
+      formatter = AwesomePrint::Formatter
+      hook = mod.name.gsub(/^.*::/, "").gsub(/(.)([A-Z])/, '\1_\2').downcase
+
+      mod.send(:alias_method, :"cast_#{hook}", :cast)
+      mod.send(:remove_method, :cast)
+
+      @list << mod
+      formatter.send(:include, mod)
+
+      puts "defining cast_with_#{hook}..."
+
+      # formatter.send(:alias_method, :"cast_without_#{hook}", :cast)
+      chain_methods(formatter, hook) do
+        formatter.send(:define_method, :"cast_with_#{hook}") do |object, type|
+          puts "cast_with_#{hook}(#{object.inspect}, #{type.inspect})"
+          cast = send(:"cast_#{hook}", object, type) || send(:"cast_without_#{hook}", object, type)
+        end
+      end
+      # formatter.send(:alias_method, :cast, :"cast_with_#{hook}")
+    end
+
+    private
+
+    def chain_methods(formatter, hook)
+      formatter.send(:alias_method, :"cast_without_#{hook}", :cast)
+      yield
+      formatter.send(:alias_method, :cast, :"cast_with_#{hook}")
+    end
   end
 end