Centralize definition of rack in formula.rb

`rack` is a commonly used alias for `formula.prefix.parent`---so common that it
gets defined and used quite a bit. This patch makes `rack` an official method
of the `Formula` class.

Library/Homebrew/build.rb

@@ -86,7 +86,7 @@ def install f
 rescue Exception
   if f.prefix.directory?
     f.prefix.rmtree
-    f.prefix.parent.rmdir_if_possible
+    f.rack.rmdir_if_possible
   end
   raise
 end

Library/Homebrew/cmd/cleanup.rb

@@ -23,25 +23,24 @@ module Homebrew extend self
 
   def cleanup_formula f
     f = Formula.factory f
-    rack = f.prefix.parent
 
     # Don't clean up keg-only brews for now.
     # Formulae link directly to them, so cleaning up old
     # ones will break already compiled software.
     if f.keg_only? and not ARGV.force?
-      opoo "Skipping keg-only #{f.name}" if rack.children.length > 1
+      opoo "Skipping keg-only #{f.name}" if f.rack.children.length > 1
       return
     end
 
-    if f.installed? and rack.directory?
-      rack.children.each do |keg|
+    if f.installed? and f.rack.directory?
+      f.rack.children.each do |keg|
         if f.installed_prefix != keg
           print "Removing #{keg}..."
           rm_rf keg
           puts
         end
       end
-    elsif rack.children.length > 1
+    elsif f.rack.children.length > 1
       # If the cellar only has one version installed, don't complain
       # that we can't tell which one to keep.
       opoo "Skipping #{f.name}: most recent version #{f.version} not installed"

Library/Homebrew/cmd/info.rb

@@ -50,9 +50,8 @@ module Homebrew extend self
 
     puts "Depends on: #{f.deps*', '}" unless f.deps.empty?
 
-    rack = f.prefix.parent
-    if rack.directory?
-      kegs = rack.children
+    if f.rack.directory?
+      kegs = f.rack.children
       kegs.each do |keg|
         next if keg.basename.to_s == '.DS_Store'
         print "#{keg} (#{keg.abv})"

Library/Homebrew/cmd/uninstall.rb

@@ -10,17 +10,16 @@ module Homebrew extend self
       end
     else
       ARGV.formulae.each do |f|
-        rack = f.prefix.parent
-        if rack.directory?
+        if f.rack.directory?
           puts "Uninstalling #{f}..."
-          rack.children.each do |keg|
+          f.rack.children.each do |keg|
             if keg.directory?
               keg = Keg.new(keg)
               keg.unlink
               keg.rmtree
             end
           end
-          rack.rmtree
+          f.rack.rmtree
         end
       end
     end

Library/Homebrew/cmd/upgrade.rb

@@ -7,12 +7,6 @@ class Fixnum
   end
 end
 
-class Formula
-  def rack
-    HOMEBREW_CELLAR/name
-  end
-end
-
 module Homebrew extend self
   def upgrade
     Homebrew.perform_preinstall_checks
@@ -23,7 +17,7 @@ module Homebrew extend self
       ARGV.formulae.map do |f|
         raise "#{f} already upgraded" if f.installed?
         raise "#{f} not installed" unless f.rack.exist? and not f.rack.children.empty?
-        [f.prefix.parent, f.name, f.version]
+        [f.rack, f.name, f.version]
       end
     end
 

Library/Homebrew/formula.rb

@@ -170,6 +170,7 @@ class Formula
     validate_variable :version
     HOMEBREW_CELLAR+@name+@version
   end
+  def rack; prefix.parent end
 
   def bin;     prefix+'bin'            end
   def doc;     prefix+'share/doc'+name end