Added rename() method to Pry#CommandSet

This enables whingers like RubyPanther to change commands such as 'ls'
to something more bland so they no longer suffer 'mental pollution'

lib/pry/command_set.rb

@@ -142,7 +142,6 @@ class Pry
       commands[name] = Command.new(name, description, options, block)
     end
 
-
     # Execute a block of code before a command is invoked. The block also
     # gets access to parameters that will be passed to the command and
     # is evaluated in the same context.
@@ -217,6 +216,9 @@ class Pry
       end
     end
 
+    # @param [String, Regexp] name_or_listing The name or listing name
+    #   of the command to retrieve.
+    # @return [Command] The command object matched.
     def find_command_by_name_or_listing(name_or_listing)
       if commands[name_or_listing]
         cmd = commands[name_or_listing]
@@ -240,6 +242,30 @@ class Pry
       commands[new_name].description = desc
     end
 
+    # Rename a command. You must use the actual name of the command,
+    # not the listing name.
+    # @param [String, Regexp] new_name The new name for the command.
+    # @param [String, Regexp] old_name The command's current name.
+    # @param [Hash] options The optional configuration parameters,
+    #   accepts the same as the `command` method, but also allows the
+    #   command description to be passed this way too.
+    # @example Renaming the `ls` command and changing its description.
+    #   Pry.config.commands.rename "dir", "ls", :description => "DOS friendly ls"
+    def rename_command(new_name, old_name, options={})
+      raise ArgumentError, "A command called '#{old_name}' was not found!" if !commands[old_name]
+      
+      options = {
+        :listing     => new_name,
+        :description => commands[old_name].description
+      }.merge!(options)
+      
+      commands[new_name] = commands[old_name]
+      commands[new_name].name = new_name
+      commands[new_name].description = options.delete(:description)
+      commands[new_name].options.merge!(options)
+      commands.delete(old_name)
+    end
+
     # Runs a command.
     # @param [Object] context Object which will be used as self during the
     #   command.

test/test_command_set.rb

@@ -271,6 +271,46 @@ describe Pry::CommandSet do
     order.should == order.sort
   end
 
+  describe "renaming a command" do
+    it 'should be able to rename and run a command' do
+      run = false
+      @set.command('foo') { run = true }
+      @set.rename_command('bar', 'foo')
+      @set.run_command(@ctx, 'bar')
+      run.should == true
+    end
+
+    it 'should not accept listing name when renaming a command' do
+      @set.command('foo', "", :listing => 'love') { }
+      lambda { @set.rename_command('bar', 'love') }.should.raise ArgumentError
+    end
+
+    it 'should be able to rename and run a command' do
+      run = false
+      @set.command('foo') { run = true }
+      @set.rename_command('bar', 'foo')
+      @set.run_command(@ctx, 'bar')
+      run.should == true
+    end
+   
+
+    it 'should make old command name inaccessible' do
+      @set.command('foo') { }
+      @set.rename_command('bar', 'foo')
+      lambda { @set.run_command(@ctx, 'foo') }.should.raise Pry::NoCommandError
+    end
+
+    it 'should be able to pass in options when renaming command' do
+      desc    = "hello"
+      listing = "bing"
+      @set.command('foo') { }
+      @set.rename_command('bar', 'foo', :description => desc, :listing => listing, :keep_retval => true)
+      @set.commands['bar'].description.should           == desc
+      @set.commands['bar'].options[:listing].should     == listing
+      @set.commands['bar'].options[:keep_retval].should == true
+    end
+  end
+
   describe "command decorators - before_command and after_command" do
     describe "before_command" do
       it 'should be called before the original command' do