Eliminate mutation of Dependency objects

Library/Homebrew/dependency.rb

@@ -4,12 +4,15 @@ require 'dependable'
 class Dependency
   include Dependable
 
-  attr_reader :name, :tags
-  attr_accessor :env_proc, :option_name
+  attr_reader :name, :tags, :env_proc, :option_name
 
-  def initialize(name, tags=[])
-    @name = @option_name = name
+  DEFAULT_ENV_PROC = proc {}
+
+  def initialize(name, tags=[], env_proc=DEFAULT_ENV_PROC, option_name=name)
+    @name = name
     @tags = tags
+    @env_proc = env_proc
+    @option_name = option_name
   end
 
   def to_s
@@ -47,10 +50,6 @@ class Dependency
     missing
   end
 
-  def universal!
-    tags << 'universal' if to_formula.build.has_option? 'universal'
-  end
-
   def modify_build_environment
     env_proc.call unless env_proc.nil?
   end
@@ -127,9 +126,7 @@ class Dependency
 
       deps.uniq.map do |dep|
         tags = grouped.fetch(dep.name).map(&:tags).flatten.uniq
-        merged_dep = dep.class.new(dep.name, tags)
-        merged_dep.env_proc = dep.env_proc
-        merged_dep
+        dep.class.new(dep.name, tags, dep.env_proc)
       end
     end
   end

Library/Homebrew/requirement.rb

@@ -70,10 +70,7 @@ class Requirement
   def to_dependency
     f = self.class.default_formula
     raise "No default formula defined for #{inspect}" if f.nil?
-    dep = Dependency.new(f, tags)
-    dep.option_name = name
-    dep.env_proc = method(:modify_build_environment)
-    dep
+    Dependency.new(f, tags, method(:modify_build_environment), name)
   end
 
   private

Library/Homebrew/test/test_dependency_expansion.rb

@@ -71,7 +71,10 @@ class DependencyExpansionTests < Test::Unit::TestCase
   end
 
   def test_merger_preserves_env_proc
-    env_proc = @foo.env_proc = stub
+    env_proc = stub
+    dep = Dependency.new("foo", [], env_proc)
+    dep.stubs(:to_formula).returns(stub(:deps => []))
+    @deps.replace [dep]
     assert_equal env_proc, Dependency.expand(@f).first.env_proc
   end