change the build directory for outside files of project

This changing will introduce:

1. When run 'rake clean', the object files of gem is not removed. To reduce the time when rebuild the project.
2. Across multiple projects that use the same gem, this changing will share the object files.
3. When update RubyMotion with 'motion update', it will remove the object files to clean up disk space.

bin/motion

@@ -12,6 +12,7 @@ $motion_libdir = File.exist?(File.join(relative_libdir, 'motion')) ? relative_li
 $:.unshift($motion_libdir)
 require 'motion/version'
 require 'motion/project/app.rb'
+require 'motion/project/builder.rb'
 
 class Command
   class << self
@@ -227,6 +228,8 @@ class UpdateCommand < Command
       $stderr.puts line
     end
     $stderr.puts "(See the `/Library/RubyMotion/NEWS' file for all changes.)"
+
+    FileUtils.rm_rf Motion::Project::Builder.common_build_dir
   end
 end
 

lib/motion/project/builder.rb

@@ -25,7 +25,7 @@ require 'thread'
 
 module Motion; module Project;
   class Builder
-    include Rake::DSL if Rake.const_defined?(:DSL)
+    include Rake::DSL if Object.const_defined?(:Rake) && Rake.const_defined?(:DSL)
 
     def build(config, platform, opts)
       datadir = config.datadir
@@ -65,10 +65,17 @@ module Motion; module Project;
       objs_build_dir = File.join(build_dir, 'objs')
       FileUtils.mkdir_p(objs_build_dir)
       any_obj_file_built = false
+      project_files = Dir.glob("**/*.rb").map{ |x| File.expand_path(x) }
+      is_default_archs = (archs == config.default_archs[platform])
+
       build_file = Proc.new do |path|
         rpath = path
         path = File.expand_path(path)
-        obj = File.join(objs_build_dir, "#{path}.o")
+        files_build_dir = objs_build_dir
+        if is_default_archs && !project_files.include?(path)
+          files_build_dir = File.expand_path(File.join(Builder.common_build_dir, files_build_dir))
+        end
+        obj = File.join(files_build_dir, "#{path}.o")
         should_rebuild = (!File.exist?(obj) \
             or File.mtime(path) > File.mtime(obj) \
             or File.mtime(ruby) > File.mtime(obj))
@@ -86,13 +93,13 @@ module Motion; module Project;
             raise "Can't locate kernel file" unless File.exist?(kernel)
    
             # LLVM bitcode.
-            bc = File.join(objs_build_dir, "#{path}.#{arch}.bc")
+            bc = File.join(files_build_dir, "#{path}.#{arch}.bc")
             bs_flags = bs_files.map { |x| "--uses-bs \"" + x + "\" " }.join(' ')
             arch_cmd = (arch =~ /^arm/) ? "/usr/bin/arch -arch i386" : "/usr/bin/arch -arch #{arch}"
             sh "/usr/bin/env VM_KERNEL_PATH=\"#{kernel}\" VM_OPT_LEVEL=\"#{config.opt_level}\" #{arch_cmd} #{ruby} #{bs_flags} --emit-llvm \"#{bc}\" #{init_func} \"#{path}\""
    
             # Assembly.
-            asm = File.join(objs_build_dir, "#{path}.#{arch}.s")
+            asm = File.join(files_build_dir, "#{path}.#{arch}.s")
             llc_arch = case arch
               when 'i386'; 'x86'
               when 'x86_64'; 'x86-64'
@@ -102,7 +109,7 @@ module Motion; module Project;
             sh "#{llc} \"#{bc}\" -o=\"#{asm}\" -march=#{llc_arch} -relocation-model=pic -disable-fp-elim -jit-enable-eh -disable-cfi"
    
             # Object.
-            arch_obj = File.join(objs_build_dir, "#{path}.#{arch}.o")
+            arch_obj = File.join(files_build_dir, "#{path}.#{arch}.o")
             sh "#{cc} -fexceptions -c -arch #{arch} \"#{asm}\" -o \"#{arch_obj}\""
   
             [bc, asm].each { |x| File.unlink(x) }
@@ -519,6 +526,16 @@ PLIST
       end
 =end
     end
+
+    class << self
+      def common_build_dir
+        dir = File.expand_path("~/Library/RubyMotion/build")
+        unless File.exist?(dir)
+          FileUtils.mkdir_p dir
+        end
+        dir
+      end
+    end
   end
 
   class Dependency

lib/motion/project/xcode_config.rb

@@ -209,16 +209,18 @@ EOS
       end
     end
 
-    def archs
-      @archs ||= begin
-        h = {}
-        platforms.each do |platform|
-          h[platform] = Dir.glob(File.join(datadir, platform, '*.bc')).map do |path|
-            path.scan(/kernel-(.+).bc$/)[0][0]
-          end
+    def default_archs
+      h = {}
+      platforms.each do |platform|
+        h[platform] = Dir.glob(File.join(datadir, platform, '*.bc')).map do |path|
+          path.scan(/kernel-(.+).bc$/)[0][0]
         end
-        h
       end
+      h
+    end
+
+    def archs
+      @archs ||= default_archs
     end
 
     def arch_flags(platform)