Fetch yields the key, use it

Library/Homebrew/macos.rb

@@ -17,8 +17,8 @@ module MacOS extend self
     # Don't call tools (cc, make, strip, etc.) directly!
     # Give the name of the binary you look for as a string to this method
     # in order to get the full path back as a Pathname.
-    (@locate ||= {}).fetch(tool.to_s) do
+    (@locate ||= {}).fetch(tool.to_s) do |key|
-      @locate[tool.to_s] = if File.executable?(path = "/usr/bin/#{tool}")
+      @locate[key] = if File.executable?(path = "/usr/bin/#{tool}")
         Pathname.new path
       # Homebrew GCCs most frequently; much faster to check this before xcrun
       # This also needs to be queried if xcrun won't work, e.g. CLT-only
@@ -76,7 +76,7 @@ module MacOS extend self
   end
 
   def sdk_path(v = version)
-    (@sdk_path ||= {}).fetch(v.to_s) do
+    (@sdk_path ||= {}).fetch(v.to_s) do |key|
       opts = []
       # First query Xcode itself
       opts << `#{locate('xcodebuild')} -version -sdk macosx#{v} Path 2>/dev/null`.chomp unless Xcode.bad_xcode_select_path?
@@ -84,7 +84,7 @@ module MacOS extend self
       opts << "#{Xcode.prefix}/Platforms/MacOSX.platform/Developer/SDKs/MacOSX#{v}.sdk"
       # Xcode < 4.3 style
       opts << "/Developer/SDKs/MacOSX#{v}.sdk"
-      @sdk_path[v.to_s] = opts.map { |a| Pathname.new(a) }.detect(&:directory?)
+      @sdk_path[key] = opts.map { |a| Pathname.new(a) }.detect(&:directory?)
     end
   end
 
@@ -250,14 +250,14 @@ module MacOS extend self
 
   def mdfind id
     return [] unless MACOS
-    (@mdfind ||= {}).fetch(id.to_s) do
+    (@mdfind ||= {}).fetch(id.to_s) do |key|
-      @mdfind[id.to_s] = `/usr/bin/mdfind "kMDItemCFBundleIdentifier == '#{id}'"`.split("\n")
+      @mdfind[key] = `/usr/bin/mdfind "kMDItemCFBundleIdentifier == '#{key}'"`.split("\n")
     end
   end
 
   def pkgutil_info id
-    (@pkginfo ||= {}).fetch(id.to_s) do
+    (@pkginfo ||= {}).fetch(id.to_s) do |key|
-      @pkginfo[id.to_s] = `/usr/sbin/pkgutil --pkg-info "#{id}" 2>/dev/null`.strip
+      @pkginfo[key] = `/usr/sbin/pkgutil --pkg-info "#{key}" 2>/dev/null`.strip
     end
   end
 end