Add option to the DSL

Closes Homebrew/homebrew#9982

Library/Homebrew/cmd/options.rb

@@ -19,9 +19,9 @@ end
 module Homebrew extend self
   def options
     ff.each do |f|
-      next if f.options.empty?
+      next if f.build.empty?
       if ARGV.include? '--compact'
-        puts f.options.collect {|o| o[0]} * " "
+        puts f.build.collect {|k,v| k} * " "
       else
         puts f.name if ff.length > 1
         dump_options_for_formula f
@@ -31,9 +31,9 @@ module Homebrew extend self
   end
 
   def dump_options_for_formula f
-    f.options.each do |o|
+    f.options.each do |k,v|
-      puts o[0]
+      puts k
-      puts "\t"+o[1]
+      puts "\t"+v
     end
   end
 end

Library/Homebrew/formula.rb

@@ -59,6 +59,9 @@ class Formula
     # If we got an explicit path, use that, else determine from the name
     @path = path.nil? ? self.class.path(name) : Pathname.new(path)
     @downloader = download_strategy.new(name, @active_spec)
+
+    # Combine DSL `option` and `def options`
+    options.each {|o| self.class.build.add(o[0], o[1]) }
   end
 
   # Derive specs from class ivars
@@ -160,6 +163,10 @@ class Formula
   def plist_name; 'homebrew.mxcl.'+name end
   def plist_path; prefix+(plist_name+'.plist') end
 
+  def build
+    self.class.build
+  end
+
   # Use the @active_spec to detect the download strategy.
   # Can be overriden to force a custom download strategy
   def download_strategy
@@ -579,6 +586,10 @@ private
       }
     end
 
+    def build
+      @build ||= BuildOptions.new(ARGV)
+    end
+
     def url val=nil, specs=nil
       if val.nil?
         return @stable.url if @stable
@@ -630,6 +641,14 @@ private
       dependencies.add(dep)
     end
 
+    def option name, description=nil
+      # Support symbols
+      name = name.to_s
+      raise "Option name is required." if name.empty?
+      raise "Options should not start with dashes." if name[0, 1] == "-"
+      build.add name, description
+    end
+
     def conflicts_with formula, opts={}
       message = <<-EOS.undent
       #{formula} cannot be installed alongside #{name.downcase}.

Library/Homebrew/formula_support.rb

@@ -151,3 +151,80 @@ EOS
     end
   end
 end
+
+
+# This class holds the build-time options defined for a Formula,
+# and provides named access to those options during install.
+class BuildOptions
+
+  def initialize args
+    # Take a copy of the args (any string array, actually)
+    @args = Array.new(args)
+    # Extend it into an ARGV extension
+    @args.extend(HomebrewArgvExtension)
+    @options = []
+  end
+
+  def add name, description=nil
+    if description.nil?
+      case name
+      when :universal, "universal"
+        description = "Build a universal binary."
+      when "32-bit"
+        description = "Build 32-bit only."
+      else
+        description = ""
+      end
+    end
+
+    @options << [name, description]
+  end
+
+  def has_option? name
+    @options.any? {|o| o[0] == name}
+  end
+
+  def empty?
+    @options.empty?
+  end
+
+  def collect
+    @options.collect {|o| yield o[0], o[1]}
+  end
+
+  def each
+    @options.each {|o| yield o[0], o[1]}
+  end
+
+  def include? name
+    @args.include? '--' + name
+  end
+
+  def using? name
+    @args.include? '--' + name
+  end
+
+  def head?
+    @args.flag? '--HEAD'
+  end
+
+  def devel?
+    @args.include? '--devel'
+  end
+
+  def stable?
+    not (head? or devel?)
+  end
+
+  # True if the user requested a universal build.
+  def universal?
+    @args.include? '--universal'
+  end
+
+  # Request a 32-bit only build.
+  # This is needed for some use-cases though we prefer to build Universal
+  # when a 32-bit version is needed.
+  def build_32_bit?
+    @args.include? '--32-bit'
+  end
+end