Update dependencies to allow constants to be defined alongside their siblings.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@5386 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

5 files changed, 233 insertions, 5 deletions

diff --git a/activesupport/CHANGELOG b/activesupport/CHANGELOG
index 8b7d421473..f383e325e9 100644
--- a/activesupport/CHANGELOG
+++ b/activesupport/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Update dependencies to allow constants to be defined alongside their siblings. A common case for this is AR model classes with STI; user.rb might define User, Administrator and Guest for example. [Nicholas Seckar]
+
 * next_week respects DST changes.  #6483 [marclove]
 
 * Expose methods added to Enumerable in the documentation, such as group_by. Closes #6170. [sergeykojin@gmail.com, Marcel Molina Jr.]
diff --git a/activesupport/lib/active_support/dependencies.rb b/activesupport/lib/active_support/dependencies.rb
index d124c657e5..270496ab15 100644
--- a/activesupport/lib/active_support/dependencies.rb
+++ b/activesupport/lib/active_support/dependencies.rb
@@ -47,6 +47,11 @@ module Dependencies #:nodoc:
   mattr_accessor :log_activity
   self.log_activity = false
   
+  # :nodoc:
+  # An internal stack used to record which constants are loaded by any block.
+  mattr_accessor :constant_watch_stack
+  self.constant_watch_stack = []
+  
   def load?
     mechanism == :load
   end
@@ -188,11 +193,13 @@ module Dependencies #:nodoc:
   def load_file(path, const_paths = loadable_constants_for_path(path))
     log_call path, const_paths
     const_paths = [const_paths].compact unless const_paths.is_a? Array
-    undefined_before = const_paths.reject(&method(:qualified_const_defined?))
+    parent_paths = const_paths.collect { |const_path| /(.*)::[^:]+\Z/ =~ const_path ? $1 : :Object }
     
-    result = load path
+    result = nil
+    newly_defined_paths = new_constants_in(*parent_paths) do
+      result = load_without_new_constant_marking path
+    end
     
-    newly_defined_paths = undefined_before.select(&method(:qualified_const_defined?))
     autoloaded_constants.concat newly_defined_paths
     autoloaded_constants.uniq!
     log "loading #{path} defined #{newly_defined_paths * ', '}" unless newly_defined_paths.empty?
@@ -290,6 +297,70 @@ module Dependencies #:nodoc:
     end
   end
   
+  # Run the provided block and detect the new constants that were loaded during
+  # its execution. Constants may only be regarded as 'new' once -- so if the
+  # block calls +new_constants_in+ again, then the constants defined within the
+  # inner call will not be reported in this one.
+  def new_constants_in(*descs)
+    log_call(*descs)
+    
+    # Build the watch frames. Each frame is a tuple of
+    #   [module_name_as_string, constants_defined_elsewhere]
+    watch_frames = descs.collect do |desc|
+      if desc.is_a? Module
+        mod_name = desc.name
+        initial_constants = desc.constants
+      elsif desc.is_a?(String) || desc.is_a?(Symbol)
+        mod_name = desc.to_s
+        
+        # Handle the case where the module has yet to be defined.
+        initial_constants = if qualified_const_defined?(mod_name)
+          mod_name.constantize.constants
+        else
+         []
+        end
+      else
+        raise Argument, "#{desc.inspect} does not describe a module!"
+      end
+      
+      [mod_name, initial_constants]
+    end
+    
+    constant_watch_stack.concat watch_frames
+    
+    yield # Now yield to the code that is to define new constants.
+    
+    # Find the new constants.
+    new_constants = watch_frames.collect do |mod_name, prior_constants|
+      # Module still doesn't exist? Treat it as if it has no constants.
+      next [] unless qualified_const_defined?(mod_name)
+      
+      mod = mod_name.constantize
+      next [] unless mod.is_a? Module
+      new_constants = mod.constants - prior_constants
+      
+      # Make sure no other frames takes credit for these constants.
+      constant_watch_stack.each do |frame_name, constants|
+        constants.concat new_constants if frame_name == mod_name
+      end
+      
+      new_constants.collect do |suffix|
+        mod_name == "Object" ? suffix : "#{mod_name}::#{suffix}"
+      end
+    end.flatten
+    
+    log "New constants: #{new_constants * ', '}"
+    return new_constants
+  ensure
+    # Remove the stack frames that we added.
+    if defined?(watch_frames) && ! watch_frames.empty?
+      frame_ids = watch_frames.collect(&:object_id)
+      constant_watch_stack.delete_if do |watch_frame|
+        frame_ids.include? watch_frame.object_id
+      end
+    end
+  end
+  
   class LoadingModule
     # Old style environment.rb referenced this method directly.  Please note, it doesn't
     # actualy *do* anything any more.
@@ -389,15 +460,18 @@ class Class
 end
 
 class Object #:nodoc:
+  
+  alias_method :load_without_new_constant_marking, :load
+  
   def load(file, *extras)
-    super(file, *extras)
+    Dependencies.new_constants_in(Object) { super(file, *extras) }
   rescue Exception => exception  # errors from loading file
     exception.blame_file! file
     raise
   end
 
   def require(file, *extras)
-    super(file, *extras)
+    Dependencies.new_constants_in(Object) { super(file, *extras) }
   rescue Exception => exception  # errors from required file
     exception.blame_file! file
     raise
diff --git a/activesupport/test/autoloading_fixtures/class_folder/nested_class.rb b/activesupport/test/autoloading_fixtures/class_folder/nested_class.rb
index 08bed842cf..77ea230d2c 100644
--- a/activesupport/test/autoloading_fixtures/class_folder/nested_class.rb
+++ b/activesupport/test/autoloading_fixtures/class_folder/nested_class.rb
@@ -1,4 +1,7 @@
 class ClassFolder
   class NestedClass
   end
+  
+  class SiblingClass
+  end
 end
diff --git a/activesupport/test/autoloading_fixtures/multiple_constant_file.rb b/activesupport/test/autoloading_fixtures/multiple_constant_file.rb
new file mode 100644
index 0000000000..a9ff4eb89c
--- /dev/null
+++ b/activesupport/test/autoloading_fixtures/multiple_constant_file.rb
@@ -0,0 +1,2 @@
+MultipleConstantFile = 10
+SiblingConstant = MultipleConstantFile * 2
diff --git a/activesupport/test/dependencies_test.rb b/activesupport/test/dependencies_test.rb
index 4065625e70..17c58eca46 100644
--- a/activesupport/test/dependencies_test.rb
+++ b/activesupport/test/dependencies_test.rb
@@ -483,4 +483,151 @@ class DependenciesTest < Test::Unit::TestCase
     end
   end
   
+  def test_new_contants_in_without_constants
+    assert_equal [], (Dependencies.new_constants_in(Object) { })
+    assert Dependencies.constant_watch_stack.empty?    
+  end
+  
+  def test_new_constants_in_with_a_single_constant
+    assert_equal(["Hello"], (Dependencies.new_constants_in(Object) do
+      Object.const_set :Hello, 10
+    end))
+    assert Dependencies.constant_watch_stack.empty?    
+  ensure
+    Object.send :remove_const, :Hello rescue nil
+  end
+  
+  def test_new_constants_in_with_nesting
+    outer = Dependencies.new_constants_in(Object) do
+      Object.const_set :OuterBefore, 10
+      
+      inner = Dependencies.new_constants_in(Object) do
+        Object.const_set :Inner, 20
+      end
+      assert_equal ["Inner"], inner
+      
+      Object.const_set :OuterAfter, 30
+    end
+    
+    assert_equal ["OuterAfter", "OuterBefore"], outer.sort
+    assert Dependencies.constant_watch_stack.empty?
+  ensure
+    %w(OuterBefore Inner OuterAfter).each do |name|
+      Object.send :remove_const, name rescue nil
+    end
+  end
+  
+  def test_new_constants_in_module
+    Object.const_set :M, Module.new
+    
+    outer = Dependencies.new_constants_in(M) do
+      M.const_set :OuterBefore, 10
+      
+      inner = Dependencies.new_constants_in(M) do
+        M.const_set :Inner, 20
+      end
+      assert_equal ["M::Inner"], inner
+      
+      M.const_set :OuterAfter, 30
+    end
+    assert_equal ["M::OuterAfter", "M::OuterBefore"], outer.sort
+    assert Dependencies.constant_watch_stack.empty?    
+  ensure
+    Object.send :remove_const, :M rescue nil
+  end
+  
+  def test_new_constants_in_module_using_name
+    outer = Dependencies.new_constants_in(:M) do
+      Object.const_set :M, Module.new
+      M.const_set :OuterBefore, 10
+      
+      inner = Dependencies.new_constants_in(:M) do
+        M.const_set :Inner, 20
+      end
+      assert_equal ["M::Inner"], inner
+      
+      M.const_set :OuterAfter, 30
+    end
+    assert_equal ["M::OuterAfter", "M::OuterBefore"], outer.sort
+    assert Dependencies.constant_watch_stack.empty?    
+  ensure
+    Object.send :remove_const, :M rescue nil
+  end
+  
+  def test_file_with_multiple_constants_and_require_dependency
+    with_loading 'autoloading_fixtures' do
+      assert ! defined?(MultipleConstantFile)
+      assert ! defined?(SiblingConstant)
+      
+      require_dependency 'multiple_constant_file'
+      assert defined?(MultipleConstantFile)
+      assert defined?(SiblingConstant)
+      assert Dependencies.autoloaded?(:MultipleConstantFile)
+      assert Dependencies.autoloaded?(:SiblingConstant)
+      
+      Dependencies.clear
+      
+      assert ! defined?(MultipleConstantFile)
+      assert ! defined?(SiblingConstant)
+    end
+  end
+  
+  def test_file_with_multiple_constants_and_auto_loading
+    with_loading 'autoloading_fixtures' do
+      assert ! defined?(MultipleConstantFile)
+      assert ! defined?(SiblingConstant)
+      
+      assert_equal 10, MultipleConstantFile
+      
+      assert defined?(MultipleConstantFile)
+      assert defined?(SiblingConstant)
+      assert Dependencies.autoloaded?(:MultipleConstantFile)
+      assert Dependencies.autoloaded?(:SiblingConstant)
+      
+      Dependencies.clear
+      
+      assert ! defined?(MultipleConstantFile)
+      assert ! defined?(SiblingConstant)
+    end
+  end
+  
+  def test_nested_file_with_multiple_constants_and_require_dependency
+    with_loading 'autoloading_fixtures' do
+      assert ! defined?(ClassFolder::NestedClass)
+      assert ! defined?(ClassFolder::SiblingClass)
+      
+      require_dependency 'class_folder/nested_class'
+      
+      assert defined?(ClassFolder::NestedClass)
+      assert defined?(ClassFolder::SiblingClass)
+      assert Dependencies.autoloaded?("ClassFolder::NestedClass")
+      assert Dependencies.autoloaded?("ClassFolder::SiblingClass")
+      
+      Dependencies.clear
+      
+      assert ! defined?(ClassFolder::NestedClass)
+      assert ! defined?(ClassFolder::SiblingClass)
+    end
+  end
+  
+  def test_nested_file_with_multiple_constants_and_auto_loading
+    with_loading 'autoloading_fixtures' do
+      assert ! defined?(ClassFolder::NestedClass)
+      assert ! defined?(ClassFolder::SiblingClass)
+      
+      assert_kind_of Class, ClassFolder::NestedClass
+      
+      assert defined?(ClassFolder::NestedClass)
+      assert defined?(ClassFolder::SiblingClass)
+      assert Dependencies.autoloaded?("ClassFolder::NestedClass")
+      assert Dependencies.autoloaded?("ClassFolder::SiblingClass")
+      
+      Dependencies.clear
+      
+      assert ! defined?(ClassFolder::NestedClass)
+      assert ! defined?(ClassFolder::SiblingClass)
+    end
+  end
+
+  
 end