Move resolve_alias from ARGV to Formula

Also, call this function from a few places where the code was duplicated.

Library/Homebrew/brew.h.rb

@@ -39,9 +39,9 @@ def __make url, name
   raise "#{path} already exists" if path.exist?
 
   if Formula.aliases.include? name and not ARGV.force?
-    realname = HOMEBREW_REPOSITORY.join("Library/Aliases/#{name}").realpath.basename('.rb')
+    realname = Formula.resolve_alias(name)
     raise <<-EOS.undent
-          The formula #{realname} is already aliased to #{name}
+          "#{name}" is an alias for formula "#{realname}".
           Please check that you are not creating a duplicate.
           To force creation use --force.
           EOS
@@ -430,8 +430,7 @@ def search_brews text
   # Filter out aliases when the full name was also found
   results.reject do |alias_name|
     if aliases.include? alias_name
-      resolved_name = (HOMEBREW_REPOSITORY+"Library/Aliases/#{alias_name}").readlink.basename('.rb').to_s
-      results.include? resolved_name
+      results.include? Formula.resolve_alias(alias_name)
     end
   end
 end

Library/Homebrew/extend/ARGV.rb

@@ -13,15 +13,16 @@ module HomebrewArgvExtension
 
   def formulae
     require 'formula'
-    @formulae ||= downcased_unique_named.map{ |name| Formula.factory(resolve_alias(name)) }
+    @formulae ||= downcased_unique_named.map{ |name| Formula.factory(Formula.resolve_alias(name)) }
     raise FormulaUnspecifiedError if @formulae.empty?
     @formulae
   end
 
   def kegs
     require 'keg'
+    require 'formula'
     @kegs ||= downcased_unique_named.collect do |name|
-      d = HOMEBREW_CELLAR + resolve_alias(name)
+      d = HOMEBREW_CELLAR + Formula.resolve_alias(name)
       dirs = d.children.select{ |pn| pn.directory? } rescue []
       raise "No such keg: #{HOMEBREW_CELLAR}/#{name}" if not d.directory? or dirs.length == 0
       raise "#{name} has multiple installed versions" if dirs.length > 1
@@ -114,15 +115,6 @@ module HomebrewArgvExtension
     EOS
   end
 
-  def resolve_alias name
-    aka = HOMEBREW_REPOSITORY+"Library/Aliases/#{name}"
-    if aka.file?
-      aka.realpath.basename('.rb').to_s
-    else
-      name
-    end
-  end
-
   private
 
   def downcased_unique_named

Library/Homebrew/formula.rb

@@ -266,6 +266,15 @@ class Formula
     Dir["#{HOMEBREW_REPOSITORY}/Library/Aliases/*"].map{ |f| File.basename f }.sort
   end
 
+  def self.resolve_alias name
+    aka = HOMEBREW_REPOSITORY+"Library/Aliases/#{name}"
+    if aka.file?
+      aka.realpath.basename('.rb').to_s
+    else
+      name
+    end
+  end
+
   def self.factory name
     return name if name.kind_of? Formula
     path = Pathname.new(name)