Add a small DSL for setting requirement options

Library/Homebrew/dependencies.rb

@@ -159,7 +159,9 @@ class Requirement
   # Should return true if this requirement is met.
   def satisfied?; false; end
   # Should return true if not meeting this requirement should fail the build.
-  def fatal?; false; end
+  def fatal?
+    self.class.fatal || false
+  end
   # The message to show when the requirement is not met.
   def message; ""; end
 
@@ -174,6 +176,12 @@ class Requirement
   def hash
     message.hash
   end
+
+  class << self
+    def fatal(val=nil)
+      val.nil? ? @fatal : @fatal = val
+    end
+  end
 end
 
 require 'requirements'

Library/Homebrew/requirements.rb

 # A dependency on a language-specific module.
 class LanguageModuleDependency < Requirement
+  fatal true
+
   def initialize language, module_name, import_name=nil
     @language = language
     @module_name = module_name
     @import_name = import_name || module_name
   end
 
-  def fatal?; true; end
-
   def satisfied?
     quiet_system(*the_test)
   end
@@ -53,14 +53,14 @@ class X11Dependency < Requirement
   include Comparable
   attr_reader :min_version
 
+  fatal true
+
   def initialize(*tags)
     tags.flatten!
     @min_version = tags.shift if /(\d\.)+\d/ === tags.first
     super
   end
 
-  def fatal?; true; end
-
   def satisfied?
     MacOS::XQuartz.installed? and (@min_version.nil? or @min_version <= MacOS::XQuartz.version)
   end
@@ -100,14 +100,14 @@ class MPIDependency < Requirement
 
   attr_reader :lang_list
 
+  fatal true
+
   def initialize *lang_list
     @lang_list = lang_list
     @non_functional = []
     @unknown_langs = []
   end
 
-  def fatal?; true; end
-
   def mpi_wrapper_works? compiler
     compiler = which compiler
     return false if compiler.nil? or not compiler.executable?
@@ -170,13 +170,15 @@ class MPIDependency < Requirement
         EOS
     end
   end
-
 end
 
 # This requirement added by the `conflicts_with` DSL method.
 class ConflictRequirement < Requirement
   attr_reader :formula
 
+  # The user can chose to force installation even in the face of conflicts.
+  fatal !ARGV.force?
+
   def initialize formula, name, opts={}
     @formula = formula
     @name = name
@@ -199,15 +201,10 @@ class ConflictRequirement < Requirement
     keg = Formula.factory(@formula).prefix
     not keg.exist? && Keg.new(keg).linked?
   end
-
-  # The user can chose to force installation even in the face of conflicts.
-  def fatal?
-    not ARGV.force?
-  end
 end
 
 class XcodeDependency < Requirement
-  def fatal?; true; end
+  fatal true
 
   def satisfied?
     MacOS::Xcode.installed?
@@ -221,7 +218,7 @@ class XcodeDependency < Requirement
 end
 
 class MysqlInstalled < Requirement
-  def fatal?; true; end
+  fatal true
 
   def satisfied?
     which 'mysql_config'
@@ -244,7 +241,7 @@ class MysqlInstalled < Requirement
 end
 
 class PostgresqlInstalled < Requirement
-  def fatal?; true; end
+  fatal true
 
   def satisfied?
     which 'pg_config'