Creating a class for carrying out rails commands.

This class encapsulates a lot of logic that wasn't very object oriented.
Helper methods have been created to try to make things more logical and
easy to read.

2 files changed, 172 insertions, 94 deletions

diff --git a/railties/lib/rails/commands.rb b/railties/lib/rails/commands.rb
index 3e8163490f..f32bf772a5 100644
--- a/railties/lib/rails/commands.rb
+++ b/railties/lib/rails/commands.rb
@@ -9,101 +9,9 @@ aliases = {
   "r"  => "runner"
 }
 
-help_message = <<-EOT
-Usage: rails COMMAND [ARGS]
-
-The most common rails commands are:
- generate    Generate new code (short-cut alias: "g")
- console     Start the Rails console (short-cut alias: "c")
- server      Start the Rails server (short-cut alias: "s")
- dbconsole   Start a console for the database specified in config/database.yml
-             (short-cut alias: "db")
- new         Create a new Rails application. "rails new my_app" creates a
-             new application called MyApp in "./my_app"
-
-In addition to those, there are:
- application  Generate the Rails application code
- destroy      Undo code generated with "generate" (short-cut alias: "d")
- plugin new   Generates skeleton for developing a Rails plugin
- runner       Run a piece of code in the application environment (short-cut alias: "r")
-
-All commands can be run with -h (or --help) for more information.
-EOT
-
-
 command = ARGV.shift
 command = aliases[command] || command
 
-case command
-when 'plugin'
-  require "rails/commands/plugin"
-when 'generate', 'destroy'
-  require 'rails/generators'
-
-  require APP_PATH
-  Rails.application.require_environment!
-
-  Rails.application.load_generators
-
-  require "rails/commands/#{command}"
-
-when 'console'
-  require 'rails/commands/console'
-  options = Rails::Console.parse_arguments(ARGV)
-
-  # RAILS_ENV needs to be set before config/application is required
-  ENV['RAILS_ENV'] = options[:environment] if options[:environment]
-
-  # shift ARGV so IRB doesn't freak
-  ARGV.shift if ARGV.first && ARGV.first[0] != '-'
-
-  require APP_PATH
-  Rails.application.require_environment!
-  Rails::Console.start(Rails.application, options)
-
-when 'server'
-  # Change to the application's path if there is no config.ru file in current directory.
-  # This allows us to run `rails server` from other directories, but still get
-  # the main config.ru and properly set the tmp directory.
-  Dir.chdir(File.expand_path('../../', APP_PATH)) unless File.exists?(File.expand_path("config.ru"))
-
-  require 'rails/commands/server'
-  Rails::Server.new.tap do |server|
-    # We need to require application after the server sets environment,
-    # otherwise the --environment option given to the server won't propagate.
-    require APP_PATH
-    Dir.chdir(Rails.application.root)
-    server.start
-  end
-
-when 'dbconsole'
-  require 'rails/commands/dbconsole'
-  Rails::DBConsole.start
-
-when 'application', 'runner'
-  require "rails/commands/#{command}"
-
-when 'new'
-  if %w(-h --help).include?(ARGV.first)
-    require 'rails/commands/application'
-  else
-    puts "Can't initialize a new Rails application within the directory of another, please change to a non-Rails directory first.\n"
-    puts "Type 'rails' for help."
-    exit(1)
-  end
-
-when '--version', '-v'
-  ARGV.unshift '--version'
-  require 'rails/commands/application'
-
-when '-h', '--help'
-  puts help_message
+require 'rails/commands/commands_tasks'
 
-else
-  puts "Error: Command '#{command}' not recognized"
-  if %x{rake #{command} --dry-run 2>&1 } && $?.success?
-    puts "Did you mean: `$ rake #{command}` ?\n\n"
-  end
-  puts help_message
-  exit(1)
-end
+Rails::CommandsTasks.new(ARGV).run_command!(command)
diff --git a/railties/lib/rails/commands/commands_tasks.rb b/railties/lib/rails/commands/commands_tasks.rb
new file mode 100644
index 0000000000..bb25d6419b
--- /dev/null
+++ b/railties/lib/rails/commands/commands_tasks.rb
@@ -0,0 +1,170 @@
+module Rails
+  # This is a class which takes in a rails command and initiates the appropriate
+  # initiation sequence.
+  #
+  # Warning: This class mutates ARGV because some commands require manipulating
+  # it before they are run.
+  class CommandsTasks # :nodoc:
+    attr_reader :argv
+
+    HELP_MESSAGE = <<-EOT
+Usage: rails COMMAND [ARGS]
+
+The most common rails commands are:
+ generate    Generate new code (short-cut alias: "g")
+ console     Start the Rails console (short-cut alias: "c")
+ server      Start the Rails server (short-cut alias: "s")
+ dbconsole   Start a console for the database specified in config/database.yml
+             (short-cut alias: "db")
+ new         Create a new Rails application. "rails new my_app" creates a
+             new application called MyApp in "./my_app"
+
+In addition to those, there are:
+ application  Generate the Rails application code
+ destroy      Undo code generated with "generate" (short-cut alias: "d")
+ plugin new   Generates skeleton for developing a Rails plugin
+ runner       Run a piece of code in the application environment (short-cut alias: "r")
+
+All commands can be run with -h (or --help) for more information.
+EOT
+
+    COMMAND_WHITELIST = %(plugin generate destroy console server dbconsole application runner new version help)
+
+    def initialize(argv)
+      @argv = argv
+    end
+
+    def run_command!(command)
+      command = parse_command(command)
+      if COMMAND_WHITELIST.include?(command)
+        send(command)
+      else
+        write_error_message(command)
+      end
+    end
+
+    def plugin
+      require_command!("plugin")
+    end
+
+    def generate
+      generate_or_destroy(:generate)
+    end
+
+    def console
+      require_command!("console")
+      options = Rails::Console.parse_arguments(argv)
+
+      # RAILS_ENV needs to be set before config/application is required
+      ENV['RAILS_ENV'] = options[:environment] if options[:environment]
+
+      # shift ARGV so IRB doesn't freak
+      shift_argv!
+
+      require_application_and_environment!
+      Rails::Console.start(Rails.application, options)
+    end
+
+    def server
+      set_application_directory!
+      require_command!("server")
+
+      Rails::Server.new.tap do |server|
+        # We need to require application after the server sets environment,
+        # otherwise the --environment option given to the server won't propagate.
+        require APP_PATH
+        Dir.chdir(Rails.application.root)
+        server.start
+      end
+    end
+
+    def dbconsole
+      require_command!("dbconsole")
+      Rails::DBConsole.start
+    end
+
+    def application
+      require_command!("application")
+    end
+
+    def runner
+      require_command!("runner")
+    end
+
+    def new
+      if %w(-h --help).include?(argv.first)
+        require_command!("application")
+      else
+        exit_with_initialization_warning!
+      end
+    end
+
+    def version
+      ARGV.unshift '--version'
+      require_command!("application")
+    end
+
+    def help
+      write_help_message
+    end
+
+    private
+
+      def exit_with_initialization_warning!
+        puts "Can't initialize a new Rails application within the directory of another, please change to a non-Rails directory first.\n"
+        puts "Type 'rails' for help."
+        exit(1)
+      end
+
+      def shift_argv!
+        ARGV.shift if ARGV.first && ARGV.first[0] != '-'
+      end
+
+      def require_command!(command)
+        require "rails/commands/#{command}"
+      end
+
+      def generate_or_destroy(command)
+        require 'rails/generators'
+        require_application_and_environment!
+        Rails.application.load_generators
+        require "rails/commands/#{command}"
+      end
+
+      # Change to the application's path if there is no config.ru file in current directory.
+      # This allows us to run `rails server` from other directories, but still get
+      # the main config.ru and properly set the tmp directory.
+      def set_application_directory!
+        Dir.chdir(File.expand_path('../../', APP_PATH)) unless File.exists?(File.expand_path("config.ru"))
+      end
+
+      def require_application_and_environment!
+        require APP_PATH
+        Rails.application.require_environment!
+      end
+
+      def write_help_message
+        puts HELP_MESSAGE
+      end
+
+      def write_error_message(command)
+        puts "Error: Command '#{command}' not recognized"
+        if %x{rake #{command} --dry-run 2>&1 } && $?.success?
+          puts "Did you mean: `$ rake #{command}` ?\n\n"
+        end
+        write_help_message
+        exit(1)
+      end
+
+      def parse_command(command)
+        case command
+        when '--version', '-v'
+          'version'
+        when '--help', '-h'
+          'help'
+        else
+          command
+        end
+      end
+  end
+end