Show debug information if --debug is supplied.

lib/thor.rb

@@ -127,24 +127,21 @@ def method_option(name, options)
     #   script.invoke(:task, first_arg, second_arg, third_arg)
     #
     def start(given_args=ARGV, config={})
-      config[:shell] ||= Thor::Base.shell.new
+      super do
+        meth = normalize_task_name(given_args.shift)
+        task = all_tasks[meth]
 
-      meth = normalize_task_name(given_args.shift)
-      task = all_tasks[meth]
+        if task
+          args, opts = Thor::Options.split(given_args)
+          config.merge!(:task_options => task.options)
+        else
+          args, opts = given_args, {}
+        end
 
-      if task
-        args, opts = Thor::Options.split(given_args)
-        config.merge!(:task_options => task.options)
-      else
-        args, opts = given_args, {}
+        task ||= Task.dynamic(meth)
+        trailing = args[Range.new(arguments.size, -1)]
+        new(args, opts, config).invoke(task, trailing || [])
       end
-
-      task ||= Task.dynamic(meth)
-      trailing = args[Range.new(arguments.size, -1)]
-
-      new(args, opts, config).invoke(task, trailing || [])
-    rescue Thor::Error => e
-      config[:shell].error e.message
     end
 
     # Prints help information. If a task name is given, it shows information

lib/thor/base.rb

@@ -341,6 +341,19 @@ def namespace(name=nil)
         end
       end
 
+      # Default way to start generators from the command line.
+      #
+      def start(given_args=ARGV, config={}) #:nodoc:
+        config[:shell] ||= Thor::Base.shell.new
+        yield
+      rescue Thor::Error => e
+        if given_args.include?("--debug")
+          raise e
+        else
+          config[:shell].error e.message
+        end
+      end
+
       protected
 
         # Prints the class options per group. If an option does not belong to

lib/thor/group.rb

@@ -22,17 +22,15 @@ def desc(description=nil)
     # inside the class.
     #
     def start(given_args=ARGV, config={})
-      config[:shell] ||= Thor::Base.shell.new
+      super do
+        if Thor::HELP_MAPPINGS.include?(given_args.first)
+          help(config[:shell])
+          return
+        end
 
-      if Thor::HELP_MAPPINGS.include?(given_args.first)
-        help(config[:shell])
-        return
+        args, opts = Thor::Options.split(given_args)
+        new(args, opts, config).invoke
       end
-
-      args, opts = Thor::Options.split(given_args)
-      new(args, opts, config).invoke
-    rescue Thor::Error => e
-      config[:shell].error e.message
     end
 
     # Prints help information.

spec/base_spec.rb

@@ -220,4 +220,12 @@ def hello
       MyCounter.get_from_super.must == 13
     end
   end
+
+  describe "#start" do
+    it "raises an error instead of rescueing if --debug is given" do
+      lambda {
+        MyScript.start ["what", "--debug"]
+      }.must raise_error(Thor::UndefinedTaskError, /the 'what' task of MyScript is private/)
+    end
+  end
 end