PyPy: also install distribute

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

Formula/pypy.rb

@@ -1,5 +1,10 @@
 require 'formula'
 
+class Distribute < Formula
+  url 'http://pypi.python.org/packages/source/d/distribute/distribute-0.6.26.tar.gz'
+  md5 '841f4262a70107f85260362f5def8206'
+end
+
 class Pypy < Formula
   homepage 'http://pypy.org/'
 
@@ -9,10 +14,82 @@ class Pypy < Formula
     md5 '1c293253e8e4df411c3dd59dff82a663'
   else
     url 'http://pypy.org/download/pypy-1.4.1-osx.tar.bz2'
+    version '1.4.1'
     md5 '8584c4e8c042f5b661fcfffa0d9b8a25'
   end
 
   def install
+    rmtree 'site-packages'
+
     prefix.install Dir['*']
+
+    # Post-install, fix up the site-packages and install-scripts folders
+    # so that user-installed Python software survives minor updates, such
+    # as going from 1.7.0 to 1.7.1.
+
+    # Create a site-packages in the prefix.
+    prefix_site_packages.mkpath
+
+    # Symlink the prefix site-packages into the cellar.
+    ln_s prefix_site_packages, prefix+'site-packages'
+
+    # Tell distutils-based installers where to put scripts
+    scripts_folder.mkpath
+    (prefix+"lib-python/modified-2.7/distutils/distutils.cfg").write <<-EOF.undent
+      [install]
+      install-scripts=#{scripts_folder}
+    EOF
+
+    # Install distribute. The user can then do:
+    # $ easy_install pip
+    # $ pip install --upgrade distribute
+    # to get newer versions of distribute outside of Homebrew.
+    Distribute.new.brew do
+      system "#{bin}/pypy", "setup.py", "install"
+
+      # Symlink to easy_install_pypy.
+      unless (scripts_folder+'easy_install_pypy').exist?
+        ln_s "#{scripts_folder}/easy_install", "#{scripts_folder}/easy_install_pypy"
+      end
+    end
+  end
+
+  def caveats
+    message = <<-EOS.undent
+    A "distutils.cfg" has been written to:
+      #{lib}/pypy/distutils
+    specifing the install-scripts folder as:
+      #{scripts_folder}
+
+    If you install Python packages via "pypy setup.py install", easy_install, pip,
+    any provided scripts will go into the install-scripts folder above, so you may
+    want to add it to your PATH.
+
+    Distribute has been installed, so easy_install is available.
+    To update distribute itself outside of Homebrew:
+        #{scripts_folder}/easy_install pip
+        #{scripts_folder}/pip install --upgrade distribute
+
+    See: https://github.com/mxcl/homebrew/wiki/Homebrew-and-Python
+    EOS
+
+    unless MacOS.prefer_64_bit?
+      message += "\n" + <<-EOS.undent
+      Outdated PyPy 1.4.1 is the last version with official 32-bit Mac binary.
+      Consider to build modern version yourself: http://pypy.org/download.html#building-from-source
+      EOS
+    end
+
+    return message
+  end
+
+  # The HOMEBREW_PREFIX location of site-packages
+  def prefix_site_packages
+    HOMEBREW_PREFIX+"lib/pypy/site-packages"
+  end
+
+  # Where distribute will install executable scripts
+  def scripts_folder
+    HOMEBREW_PREFIX+"share/pypy"
   end
 end