PORTREVISION=	1

diff --git a/clamp-0.6.3.gemspec b/clamp-0.6.3.gemspec

index 8f51cc3..acab485 100644

--- clamp-0.6.3.gemspec

+++ clamp-0.6.3.gemspec

@@ -43,6 +43,7 @@

 - lib/clamp/command.rb

 - lib/clamp/errors.rb

 - lib/clamp/help.rb

+- lib/clamp/messages.rb

 - lib/clamp/option/declaration.rb

 - lib/clamp/option/definition.rb

 - lib/clamp/option/parsing.rb

diff --git a/lib/clamp/attribute/instance.rb b/lib/clamp/attribute/instance.rb

index 8f51cc3..acab485 100644

--- lib/clamp/attribute/instance.rb

+++ lib/clamp/attribute/instance.rb

@@ -72,7 +72,7 @@ def default_from_environment

         begin

           take(value)

         rescue ArgumentError => e

-          command.send(:signal_usage_error, "$#{attribute.environment_variable}: #{e.message}")

+          command.send(:signal_usage_error, Clamp.message(:env_argument_error, :env => attribute.environment_variable, :message => e.message))

         end

       end

diff --git a/lib/clamp/command.rb b/lib/clamp/command.rb

index c6c50f4..52187ab 100644

--- lib/clamp/command.rb

+++ lib/clamp/command.rb

@@ -1,3 +1,4 @@

+require 'clamp/messages'

 require 'clamp/errors'

 require 'clamp/help'

 require 'clamp/option/declaration'

@@ -91,7 +92,7 @@ def help

     def handle_remaining_arguments

       unless remaining_arguments.empty?

-        signal_usage_error "too many arguments"

+        signal_usage_error Clamp.message(:too_many_arguments)

       end

     end

diff --git a/lib/clamp/help.rb b/lib/clamp/help.rb

index e09731a..1e57530 100644

--- lib/clamp/help.rb

+++ lib/clamp/help.rb

@@ -61,7 +61,7 @@ def string

       end

       def add_usage(invocation_path, usage_descriptions)

-        puts "Usage:"

+        puts usage_heading

         usage_descriptions.each do |usage|

           puts "    #{invocation_path} #{usage}".rstrip

         end

@@ -87,6 +87,12 @@ def add_list(heading, items)

         end

       end

+      protected

+

+      def usage_heading

+        "Usage:"

+      end

+

       private

       def puts(*args)

diff --git a/lib/clamp/messages.rb b/lib/clamp/messages.rb

new file mode 100644

index 0000000..61cce94

--- /dev/null

+++ lib/clamp/messages.rb

@@ -0,0 +1,39 @@

+module Clamp

+

+  def self.messages=(messages)

+    @user_defined_messages = messages

+  end

+

+  def self.message(key, options={})

+    @user_defined_messages ||= {}

+    msg = @user_defined_messages[key] || messages[key]

+    format_string(msg, options)

+  end

+

+  def self.messages

+    {

+      :too_many_arguments => "too many arguments",

+      :option_required => "option '%<option>s' is required",

+      :option_or_env_required => "option '%<option>s' (or env %<env>s) is required",

+      :option_argument_error => "option '%<switch>s': %<message>s",

+      :parameter_argument_error => "parameter '%<param>s': %<message>s",

+      :env_argument_error => "$%<env>s: %<message>s",

+      :unrecognised_option => "Unrecognised option '%<switch>s'",

+      :no_such_subcommand => "No such sub-command '%<name>s'",

+      :no_value_provided => "no value provided"

+    }

+  end

+

+  private

+

+  # string formatting for ruby 1.8

+  def self.format_string(string, params)

+    array_params = string.scan(/%[<{]([^>}]*)[>}]/).collect do |name|

+      name = name[0]

+      params[name.to_s] || params[name.to_sym]

+    end

+

+    string.gsub(/%[<]([^>]*)[>]/, '%').gsub(/%[{]([^}]*)[}]/, '%s') % array_params

+  end

+

+end

diff --git a/lib/clamp/option/parsing.rb b/lib/clamp/option/parsing.rb

index 9f057f1..bb7b41c 100644

--- lib/clamp/option/parsing.rb

+++ lib/clamp/option/parsing.rb

@@ -31,7 +31,7 @@ def parse_options

           begin

             option.of(self).take(value)

           rescue ArgumentError => e

-            signal_usage_error "option '#{switch}': #{e.message}"

+            signal_usage_error Clamp.message(:option_argument_error, :switch => switch, :message => e.message)

           end

         end

@@ -45,11 +45,11 @@ def parse_options

         self.class.recognised_options.each do |option|

           # If this option is required and the value is nil, there's an error.

           if option.required? and send(option.attribute_name).nil?

-            message = "option '#{option.switches.first}'"

             if option.environment_variable

-              message += " (or env #{option.environment_variable})"

+              message = Clamp.message(:option_or_env_required, :option => option.switches.first, :env => option.environment_variable)

+            else

+              message = Clamp.message(:option_required, :option => option.switches.first)

             end

-            message += " is required"

             signal_usage_error message

           end

         end

@@ -59,7 +59,7 @@ def parse_options

       def find_option(switch)

         self.class.find_option(switch) ||

-        signal_usage_error("Unrecognised option '#{switch}'")

+        signal_usage_error(Clamp.message(:unrecognised_option, :switch => switch))

       end

     end

diff --git a/lib/clamp/parameter/definition.rb b/lib/clamp/parameter/definition.rb

index 6412546..a276dea 100644

--- lib/clamp/parameter/definition.rb

+++ lib/clamp/parameter/definition.rb

@@ -22,7 +22,7 @@ def help_lhs

       end

       def consume(arguments)

-        raise ArgumentError, "no value provided" if required? && arguments.empty?

+        raise ArgumentError, Clamp.message(:no_value_provided) if required? && arguments.empty?

         arguments.shift(multivalued? ? arguments.length : 1)

       end

diff --git a/lib/clamp/parameter/parsing.rb b/lib/clamp/parameter/parsing.rb

index 8a70719..95aa422 100644

--- lib/clamp/parameter/parsing.rb

+++ lib/clamp/parameter/parsing.rb

@@ -13,7 +13,7 @@ def parse_parameters

               parameter.of(self).take(value)

             end

           rescue ArgumentError => e

-            signal_usage_error "parameter '#{parameter.name}': #{e.message}"

+            signal_usage_error Clamp.message(:parameter_argument_error, :param => parameter.name, :message => e.message)

           end

         end

diff --git a/lib/clamp/subcommand/execution.rb b/lib/clamp/subcommand/execution.rb

index d15c56b..c341df6 100644

--- lib/clamp/subcommand/execution.rb

+++ lib/clamp/subcommand/execution.rb

@@ -25,7 +25,7 @@ def instatiate_subcommand(name)

       end

       def find_subcommand_class(name)

-        subcommand_def = self.class.find_subcommand(name) || signal_usage_error("No such sub-command '#{name}'")

+        subcommand_def = self.class.find_subcommand(name) || signal_usage_error(Clamp.message(:no_such_subcommand, :name => name))

         subcommand_def.subcommand_class

       end