Add depends_on, use, and setup to abstract up ideas about module inheritance.

2 files changed, 27 insertions, 0 deletions

diff --git a/activesupport/lib/active_support/core_ext/module.rb b/activesupport/lib/active_support/core_ext/module.rb
index da8d28ec13..cb31437094 100644
--- a/activesupport/lib/active_support/core_ext/module.rb
+++ b/activesupport/lib/active_support/core_ext/module.rb
@@ -8,6 +8,7 @@ require 'active_support/core_ext/module/loading'
 require 'active_support/core_ext/module/aliasing'
 require 'active_support/core_ext/module/model_naming'
 require 'active_support/core_ext/module/synchronization'
+require 'active_support/core_ext/module/setup'
 
 module ActiveSupport
   module CoreExtensions
diff --git a/activesupport/lib/active_support/core_ext/module/setup.rb b/activesupport/lib/active_support/core_ext/module/setup.rb
new file mode 100644
index 0000000000..e6dfd0cf56
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/module/setup.rb
@@ -0,0 +1,26 @@
+class Module
+  attr_accessor :_setup_block
+  attr_accessor :_dependencies
+  
+  def setup(&blk)
+    @_setup_block = blk
+  end
+  
+  def use(mod)
+    return if self < mod
+    
+    (mod._dependencies || []).each do |dep|
+      use dep
+    end
+    # raise "Circular dependencies" if self < mod
+    include mod
+    extend mod.const_get("ClassMethods") if mod.const_defined?("ClassMethods")
+    class_eval(&mod._setup_block) if mod._setup_block
+  end
+  
+  def depends_on(mod)
+    return if self < mod
+    @_dependencies ||= []
+    @_dependencies << mod
+  end
+end
\ No newline at end of file