Commands can now be registered as subcommands (similar to how config works)

lib/vagrant/command.rb

@@ -21,18 +21,7 @@ module Vagrant
     # Execute a subcommand with the given name and args. This method properly
     # finds the subcommand, instantiates it, and executes.
     def subcommand(name, *args)
-      command_klass = Commands.const_get(camelize(name))
-      command = command_klass.new(env)
-      command.execute(args)
-    end
-
-    # Camel-case a string.
-    def camelize(string)
-      parts = string.to_s.split(/[^a-z0-9]/).collect do |part|
-        part.capitalize
-      end
-
-      parts.join("")
+      Commands::Base.dispatch(env, name, *args)
     end
   end
 end

lib/vagrant/commands/base.rb

@@ -7,6 +7,61 @@ module Vagrant
     class Base
       attr_reader :env
 
+      class <<self
+        # Contains the list of registered subcommands. The registered commands are
+        # stored in a hash table and are therefore unordered.
+        #
+        # @return [Hash]
+        def subcommands
+          @subcommands ||= {}
+        end
+
+        # Registers a command with `vagrant`. This method allows 3rd parties to
+        # dynamically add new commands to the `vagrant` command, allowing plugins
+        # to act as 1st class citizens within vagrant.
+        #
+        # @param [String] key The subcommand which will invoke the registered command.
+        # @param [Class] klass. The subcommand class (a subclass of {Base})
+        def subcommand(key, klass)
+          subcommands[key] = klass
+        end
+
+        # Dispatches a subcommand to the proper registered command. Otherwise, it
+        # prints a help message.
+        def dispatch(env, name, *args)
+          klass = subcommands[name]
+          if klass.nil?
+            puts_help
+            return # For tests
+          end
+
+          command = klass.new(env)
+          command.execute(args)
+        end
+
+        # Prints out the list of supported commands and their descriptions (if
+        # available) then exits.
+        def puts_help
+          puts "Usage: vagrant SUBCOMMAND ...\n\n"
+
+          puts "Supported commands:"
+          subcommands.each do |key, klass|
+            puts "#{' ' * 4}#{key.ljust(20)}#{klass.description}"
+          end
+
+          exit
+        end
+
+        # Sets or reads the description, depending on if the value is set in the
+        # parameter.
+        def description(value=nil)
+          @description ||= ''
+
+          return @description if value.nil?
+          @description = value
+        end
+      end
+
       def initialize(env)
         @env = env
       end

lib/vagrant/commands/init.rb

@@ -1,10 +1,15 @@
 module Vagrant
   class Commands
     class Init < Base
+      Base.subcommand "init", self
+      description "Initializes current folder for Vagrant usage"
+
       def execute(args)
         parse_options(args) do |opts, options|
           opts.banner = "Usage: vagrant init [name]"
         end
+
+        puts "HEY"
       end
     end
   end

test/vagrant/command_test.rb

@@ -43,28 +43,10 @@ class CommandTest < Test::Unit::TestCase
         @instance.stubs(:camelize).with(@raw_name).returns(@name)
       end
 
-      should "send the command to the proper class" do
-        klass = mock("klass")
-        instance = mock("instance")
+      should "send the env, name, and args to the base class" do
         args = [1,2,3]
-        Vagrant::Commands.expects(:const_get).with(@name).returns(klass)
-        klass.expects(:new).with(@env).returns(instance)
-        instance.expects(:execute).with(args)
-
-        @instance.subcommand(@raw_name, *args)
-      end
-    end
-
-    context "camelizing" do
-      should "camel case a string" do
-        tests = {
-          "foo_bar_baz" => "FooBarBaz",
-          "ssh-config" => "SshConfig"
-        }
-
-        tests.each do |test, expected|
-          assert_equal expected, @instance.camelize(test)
-        end
+        Vagrant::Commands::Base.expects(:dispatch).with(@env, @name, *args)
+        @instance.subcommand(@name, *args)
       end
     end
   end

test/vagrant/commands/base_test.rb

@@ -13,6 +13,51 @@ class CommandsBastTest < Test::Unit::TestCase
     end
   end
 
+  context "class methods" do
+    setup do
+      @klass.subcommands.clear
+    end
+
+    context "registering commands" do
+      should "register commands" do
+        klass = mock("klass")
+        @klass.subcommand("init", klass)
+        assert_equal klass, @klass.subcommands["init"]
+      end
+    end
+
+    context "dispatching to subcommands" do
+      setup do
+        @command_klass = mock("klass")
+        @name = "init"
+        @klass.subcommand(@name, @command_klass)
+
+        @args = [1,2,3]
+      end
+
+      should "instantiate and execute on registered subcommands" do
+        instance = mock("instance")
+        @command_klass.expects(:new).with(@env).returns(instance)
+        instance.expects(:execute).with(@args)
+
+        @klass.dispatch(@env, @name, *@args)
+      end
+
+      should "print help if command doesn't exist" do
+        @klass.expects(:puts_help).once
+        @klass.dispatch(@env, "#{@name}foo")
+      end
+    end
+
+    context "descriptions" do
+      should "be able to set description" do
+        description = "The lazy fox yada yada"
+        @klass.description(description)
+        assert_equal description, @klass.description
+      end
+    end
+  end
+
   context "instance methods" do
     setup do
       @env = mock_environment