Remove <=> from Dependency interface

It is important that dep equality corresponds to the name attribute, but
we may want to use the Comparable interface to sort them by installation
order in the future. Code that needs to sort them alphabetically should
just use sort_by.

Library/Homebrew/cmd/deps.rb

@@ -22,7 +22,9 @@ module Homebrew extend self
       end
     else
       raise FormulaUnspecifiedError if ARGV.named.empty?
-      all_deps = ARGV.formulae.map{ |f| ARGV.one? ? f.deps : f.recursive_deps }.intersection
+      all_deps = ARGV.formulae.map do |f|
+        ARGV.one? ? f.deps : f.recursive_deps
+      end.intersection.map(&:name)
       all_deps.sort! unless ARGV.include? "-n"
       puts all_deps
     end

Library/Homebrew/dependencies.rb

@@ -145,27 +145,23 @@ class Dependency
 
   def initialize(name, *tags)
     @name = name
-    @tags = [tags].flatten.compact
-  end
-
-  def hash
-    @name.hash
+    @tags = tags.flatten.compact
   end
 
   def to_s
-    @name
+    name
   end
 
   def ==(other)
-    @name == other.to_s
-  end
-
-  def <=>(other)
-    @name <=> other.to_s
+    name == other.name
   end
 
   def eql?(other)
-    other.is_a? self.class and hash == other.hash
+    other.is_a?(self.class) && hash == other.hash
+  end
+
+  def hash
+    name.hash
   end
 end
 
@@ -199,7 +195,7 @@ class Requirement
   end
 
   def eql?(other)
-    other.is_a? self.class and hash == other.hash
+    other.is_a?(self.class) && hash == other.hash
   end
 
   def hash

Library/Homebrew/test/test_dependencies.rb

@@ -75,17 +75,48 @@ end
 class DependableTests < Test::Unit::TestCase
   def setup
     @tags = ["foo", "bar", :build]
-    @deps = Struct.new(:tags).new(@tags)
-    @deps.extend(Dependable)
+    @dep = Struct.new(:tags).new(@tags).extend(Dependable)
   end
 
   def test_options
-    assert_equal %w{--foo --bar}.sort, @deps.options.sort
+    assert_equal %w{--foo --bar}.sort, @dep.options.sort
   end
 
   def test_interrogation
-    assert @deps.build?
-    assert !@deps.optional?
-    assert !@deps.recommended?
+    assert @dep.build?
+    assert !@dep.optional?
+    assert !@dep.recommended?
+  end
+end
+
+class DependencyTests < Test::Unit::TestCase
+  def test_accepts_single_tag
+    dep = Dependency.new("foo", "bar")
+    assert_equal %w{bar}, dep.tags
+  end
+
+  def test_accepts_multiple_tags
+    dep = Dependency.new("foo", %w{bar baz})
+    assert_equal %w{bar baz}.sort, dep.tags.sort
+  end
+
+  def test_preserves_symbol_tags
+    dep = Dependency.new("foo", :build)
+    assert_equal [:build], dep.tags
+  end
+
+  def test_accepts_symbol_and_string_tags
+    dep = Dependency.new("foo", [:build, "bar"])
+    assert_equal [:build, "bar"], dep.tags
+  end
+
+  def test_equality
+    foo1 = Dependency.new("foo")
+    foo2 = Dependency.new("foo")
+    bar = Dependency.new("bar")
+    assert_equal foo1, foo2
+    assert foo1.eql?(foo2)
+    assert_not_equal foo1, bar
+    assert !foo1.eql?(bar)
   end
 end