Add extension mechanism for custom ST operations

git-svn-id: http://svn.rubyonrails.org/rails/tools/switchtower@3604 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

CHANGELOG

@@ -1,5 +1,7 @@
 *0.11.0* *SVN*
 
+* Add extension mechanism for custom ST operations
+
 * Make ST rails rake tasks more configurable
 
 * Add Actor#current_task and simplify Task#servers

lib/switchtower/configuration.rb

@@ -1,6 +1,7 @@
 require 'switchtower/actor'
 require 'switchtower/logger'
 require 'switchtower/scm/subversion'
+require 'switchtower/extensions'
 
 module SwitchTower
   # Represents a specific SwitchTower configuration. A Configuration instance

lib/switchtower/extensions.rb

@@ -0,0 +1,38 @@
+require 'switchtower/actor'
+
+module SwitchTower
+  class ExtensionProxy
+    def initialize(actor, mod)
+      @actor = actor
+      extend(mod)
+    end
+
+    def method_missing(sym, *args, &block)
+      @actor.send(sym, *args, &block)
+    end
+  end
+
+  EXTENSIONS = {}
+
+  def self.plugin(name, mod)
+    return false if EXTENSIONS.has_key?(name)
+
+    SwitchTower::Actor.class_eval <<-STR, __FILE__, __LINE__+1
+      def #{name}
+        @__#{name}_proxy ||= SwitchTower::ExtensionProxy.new(self, SwitchTower::EXTENSIONS[#{name.inspect}])
+      end
+    STR
+
+    EXTENSIONS[name] = mod
+    return true
+  end
+
+  def self.remove_plugin(name)
+    if EXTENSIONS.delete(name)
+      SwitchTower::Actor.send(:remove_method, name)
+      return true
+    end
+
+    return false
+  end
+end

test/actor_test.rb

@@ -84,6 +84,12 @@ class ActorTest < Test::Unit::TestCase
     end
   end
 
+  module CustomExtension
+    def do_something_extra(a, b, c)
+      run "echo '#{a} :: #{b} :: #{c}'"
+    end
+  end
+
   def setup
     TestingCommand.reset!
     @actor = TestActor.new(MockConfiguration.new)
@@ -275,4 +281,14 @@ class ActorTest < Test::Unit::TestCase
 
     assert_raises(RuntimeError) { @actor.foo }
   end
+
+  def test_custom_extension
+    assert SwitchTower.plugin(:custom, CustomExtension)
+    @actor.define_task :foo, :roles => :db do
+      custom.do_something_extra(1, 2, 3)
+    end
+    assert_nothing_raised { @actor.foo }
+    assert TestingCommand.invoked?
+    assert SwitchTower.remove_plugin(:custom)
+  end
 end