Clean up Tab creation

Library/Homebrew/formula_installer.rb

@@ -243,7 +243,7 @@ class FormulaInstaller
 
     raise "Empty installation" if Dir["#{f.prefix}/*"].empty?
 
-    Tab.for_install(f, args).write # INSTALL_RECEIPT.json
+    Tab.create(f, args).write # INSTALL_RECEIPT.json
 
   rescue Exception => e
     ignore_interrupts do

Library/Homebrew/tab.rb

@@ -1,18 +1,22 @@
 require 'ostruct'
-
 require 'formula'
 require 'vendor/multi_json'
 
 # Inherit from OpenStruct to gain a generic initialization method that takes a
 # hash and creates an attribute for each key and value. `Tab.new` probably
 # should not be called directly, instead use one of the class methods like
-# `Tab.for_install`.
+# `Tab.create`.
 class Tab < OpenStruct
-  def self.for_install f, args
-    sha = `cd '#{HOMEBREW_REPOSITORY}' && git rev-parse --verify -q HEAD 2>/dev/null`.chuzzle
+  FILENAME = 'INSTALL_RECEIPT.json'
+
+  def self.create f, args
+    sha = HOMEBREW_REPOSITORY.cd do
+      `git rev-parse --verify -q HEAD 2>/dev/null`.chuzzle
+    end
+
     Tab.new :used_options => args.used_options(f),
             :unused_options => args.unused_options(f),
-            :tabfile => f.prefix + "INSTALL_RECEIPT.json",
+            :tabfile => f.prefix.join(FILENAME),
             :built_as_bottle => !!args.build_bottle?,
             :tapped_from => f.tap,
             :time => Time.now.to_i, # to_s would be better but Ruby has no from_s function :P
@@ -22,50 +26,29 @@ class Tab < OpenStruct
   def self.from_file path
     tab = Tab.new MultiJson.decode(open(path).read)
     tab.tabfile = path
-    return tab
+    tab
   end
 
   def self.for_keg keg
-    path = keg+'INSTALL_RECEIPT.json'
+    path = keg.join(FILENAME)
 
     if path.exist?
-      self.from_file path
+      self.from_file(path)
     else
-      begin
-        self.dummy_tab Formula.factory(keg.parent.basename)
-      rescue FormulaUnavailableError
-        Tab.new :used_options => [],
-                :unused_options => [],
-                :built_as_bottle => false,
-                :tapped_from => "",
-                :time => nil,
-                :HEAD => nil
-      end
+      self.dummy_tab
     end
   end
 
   def self.for_formula f
-    f = Formula.factory f unless f.kind_of? Formula
-    path = f.linked_keg/'INSTALL_RECEIPT.json'
-
-    if path.exist?
-      self.from_file path
-    else
-      # Really should bail out with an error if a formula was not installed
-      # with a Tab. However, there will be lots of legacy installs that have no
-      # receipt---so we fabricate one that claims the formula was installed with
-      # no options.
-      #
-      # TODO:
-      # This isn't the best behavior---perhaps a future version of Homebrew can
-      # treat missing Tabs as errors.
-      self.dummy_tab f
-    end
+    f = Formula.factory(f)
+    path = [f.opt_prefix, f.linked_keg].map{ |pn| pn.join(FILENAME) }.find{ |pn| pn.exist? }
+    # Legacy kegs may lack a receipt. If it doesn't exist, fake one
+    if path.nil? then self.dummy_tab(f) else self.from_file(path) end
   end
 
-  def self.dummy_tab f
+  def self.dummy_tab f=nil
     Tab.new :used_options => [],
-            :unused_options => f.build.as_flags,
+            :unused_options => (f.build.as_flags rescue []),
             :built_as_bottle => false,
             :tapped_from => "",
             :time => nil,