Solving the GNU GetText issues

GNU GetText breaks eg. Ruby 1.9 builds, and some other formula I have been building too. But it is required by eg. glib. So to solve this we are going to by default not symlink gettext into the Homebrew prefix.

Formula that depend on GetText will have the gettext paths added to the brewing environment automatically. Neat.

Library/Homebrew/brewkit.rb

@@ -143,6 +143,14 @@ module HomebrewEnvExtension
   def enable_warnings
     remove_from_cflags '-w'
   end
+  # so yeah, GNU gettext is a funny one, if you want to use it, you need to
+  # call this function, see gettext.rb for info.
+  def gnu_gettext
+    gettext = Formula.factory 'gettext'
+    ENV['LDFLAGS'] += " -L#{gettext.lib}"
+    ENV['CPPFLAGS'] = "#{ENV['CPPFLAGS']} -I#{gettext.include}"
+    ENV['PATH'] += ":#{gettext.bin}"
+  end
 
 private
   def append key, value

Library/Homebrew/formula.rb

@@ -114,13 +114,16 @@ class Formula
   #     :p1 =>  'http://bar.com/patch2',
   #     :p2 => ['http://moo.com/patch5', 'http://moo.com/patch6']
   #   }
-  # The final option is to return DATA, then put a diff after __END__ and you
+  # The final option is to return DATA, then put a diff after __END__. You
   # can still return a Hash with DATA as the value for a patch level key.
   def patches; end
   # reimplement and specify dependencies
   def deps; end
   # sometimes the clean process breaks things, return true to skip anything
   def skip_clean? path; false end
+  # rarely, you don't want your library symlinked into the main prefix
+  # see gettext.rb for an example
+  def keg_only?; false end
 
   # yields self with current working directory set to the uncompressed tarball
   def brew

Library/Homebrew/install.rb

@@ -6,6 +6,21 @@ require 'brew.h'
 
 show_summary_heading = false
 
+def text_for_keg_only_formula f
+  <<-EOS
+#{f.name} is keg-only. This means it is not symlinked into Homebrew's
+prefix. The formula provides the following rationale:
+
+#{f.keg_only?}
+
+Generally there are no consequences of this for you, however if you build your
+own software and it requires this formula, you may want to run this command to
+link it into the Homebrew prefix:
+
+     brew link #{f.name}
+  EOS
+end
+
 def install f  
   build_time = nil
 
@@ -71,14 +86,19 @@ def install f
     end
   end
 
-  begin
-    Keg.new(f.prefix).link
-  rescue Exception
-    onoe "The linking step did not complete successfully"
-    puts "The package built, but is not symlinked into #{HOMEBREW_PREFIX}"
-    puts "You can try again using `brew link #{f.name}'"
-    ohai e, e.inspect if ARGV.debug?
+  if f.keg_only?
+    ohai 'Caveats', text_for_keg_only_formula(f)
     show_summary_heading = true
+  else
+    begin
+      Keg.new(f.prefix).link
+    rescue Exception
+      onoe "The linking step did not complete successfully"
+      puts "The package built, but is not symlinked into #{HOMEBREW_PREFIX}"
+      puts "You can try again using `brew link #{f.name}'"
+      ohai e, e.inspect if ARGV.debug?
+      show_summary_heading = true
+    end
   end
 
   ohai "Summary" if ARGV.verbose? or show_summary_heading