5 files changed, 65 insertions, 26 deletions
diff --git a/Library/Homebrew/build_environment.rb b/Library/Homebrew/build_environment.rb
index 97a8fae42..18876f954 100644
--- a/Library/Homebrew/build_environment.rb
+++ b/Library/Homebrew/build_environment.rb
@@ -17,4 +17,29 @@ class BuildEnvironment
   def userpaths?
     @settings.include? :userpaths
   end
+
+  def modify_build_environment
+    p = @settings.find { |s| Proc === s }
+    ENV.instance_eval(&p) unless p.nil?
+  end
+
+  def _dump(*)
+    @settings.dup.reject { |s| Proc === s }.join(":")
+  end
+
+  def self._load(s)
+    new(*s.split(":").map(&:to_sym))
+  end
+end
+
+module BuildEnvironmentDSL
+  def env(*settings, &block)
+    @env ||= BuildEnvironment.new
+    if block_given?
+      @env << block
+    else
+      settings.each { |s| @env << s }
+    end
+    @env
+  end
 end
diff --git a/Library/Homebrew/dependencies.rb b/Library/Homebrew/dependencies.rb
index 623591c78..c2dd63d7d 100644
--- a/Library/Homebrew/dependencies.rb
+++ b/Library/Homebrew/dependencies.rb
@@ -170,6 +170,7 @@ end
 # By default, Requirements are non-fatal.
 class Requirement
   include Dependable
+  extend BuildEnvironmentDSL
 
   attr_reader :tags
 
@@ -186,9 +187,11 @@ class Requirement
   # The message to show when the requirement is not met.
   def message; ""; end
 
-  # Requirements can modify the current build environment by overriding this.
-  # See X11Dependency
-  def modify_build_environment; nil end
+  # Overriding modify_build_environment is deprecated, pass a block to
+  # the env DSL method instead.
+  def modify_build_environment
+    env.modify_build_environment
+  end
 
   def env
     @env ||= self.class.env
@@ -206,12 +209,6 @@ class Requirement
     def fatal(val=nil)
       val.nil? ? @fatal : @fatal = val
     end
-
-    def env(*settings)
-      @env ||= BuildEnvironment.new
-      settings.each { |s| @env << s }
-      @env
-    end
   end
 end
 
diff --git a/Library/Homebrew/formula.rb b/Library/Homebrew/formula.rb
index b7256ff0f..b78434b91 100644
--- a/Library/Homebrew/formula.rb
+++ b/Library/Homebrew/formula.rb
@@ -11,6 +11,7 @@ require 'extend/set'
 
 class Formula
   include FileUtils
+  extend BuildEnvironmentDSL
 
   attr_reader :name, :path, :homepage, :downloader
   attr_reader :stable, :bottle, :devel, :head, :active_spec
@@ -727,12 +728,6 @@ private
       @stable.mirror(val)
     end
 
-    def env *settings
-      @env ||= BuildEnvironment.new
-      settings.each { |s| @env << s }
-      @env
-    end
-
     def dependencies
       @dependencies ||= DependencyCollector.new
     end
diff --git a/Library/Homebrew/test/test_build_environment.rb b/Library/Homebrew/test/test_build_environment.rb
index fde3f3c70..d8a227f51 100644
--- a/Library/Homebrew/test/test_build_environment.rb
+++ b/Library/Homebrew/test/test_build_environment.rb
@@ -19,4 +19,37 @@ class BuildEnvironmentTests < Test::Unit::TestCase
     @env << :userpaths
     assert @env.userpaths?
   end
+
+  def test_modify_build_environment
+    @env << Proc.new { 1 }
+    assert_equal 1, @env.modify_build_environment
+  end
+
+  def test_marshal
+    @env << :userpaths
+    @env << Proc.new { 1 }
+    dump = Marshal.dump(@env)
+    assert Marshal.load(dump).userpaths?
+  end
+end
+
+class BuildEnvironmentDSLTests < Test::Unit::TestCase
+  def make_instance(&block)
+    Class.new do
+      extend BuildEnvironmentDSL
+      def env; self.class.env end
+      class_eval(&block)
+    end.new
+  end
+
+  def test_env_single_argument
+    obj = make_instance { env :userpaths }
+    assert obj.env.userpaths?
+  end
+
+  def test_env_multiple_arguments
+    obj = make_instance { env :userpaths, :std }
+    assert obj.env.userpaths?
+    assert obj.env.std?
+  end
 end
diff --git a/Library/Homebrew/test/test_requirement.rb b/Library/Homebrew/test/test_requirement.rb
index 7bfb75ff3..28e2afae7 100644
--- a/Library/Homebrew/test/test_requirement.rb
+++ b/Library/Homebrew/test/test_requirement.rb
@@ -26,17 +26,6 @@ class RequirementTests < Test::Unit::TestCase
     assert_equal [:build, "bar"], dep.tags
   end
 
-  def test_dsl_env_single_argument
-    req = Class.new(Requirement) { env :userpaths }.new
-    assert req.env.userpaths?
-  end
-
-  def test_dsl_env_multiple_arguments
-    req = Class.new(Requirement) { env :userpaths, :std }.new
-    assert req.env.userpaths?
-    assert req.env.std?
-  end
-
   def test_dsl_fatal
     req = Class.new(Requirement) { fatal true }.new
     assert req.fatal?