Python 2.x and 3.x support

New `depends_on :python` Dependency.
New `depends_on :python3` Dependency.

To avoid having multiple formulae with endings -py2 and -py3,
we will handle support for different pythons (2.x vs. 3.x)
in the same formula.
Further brewed vs. external python will be transparently supported.

The formula also gets a new object `python`, which is false if
no Python is available or the user has disabled it. Otherwise
it is defined and provides several support methods:

python.site_packages # the site-packages in the formula's Cellar
python.global_site_packages
python.binary # the full path to the python binary
python.prefix
python.version
python.version.major
python.version.minor
python.xy # => e.g. "python2.7"
python.incdir # includes of python
python.libdir # the python dylib library
python.pkg_config_path # used internally by brew
python.from_osx?
python.framework?
python.universal?
python.pypy?
python.standard_caveats # Text to set PYTHONPATH for python.from_osx?
python.if3then3 # => "" for 2.x and to "3" for 3.x.

Further, to avoid code duplication, `python` takes an optional
block that is run twice if the formula defines depends_on
:python AND :python3.

python do
  system python, 'setup.py', "--prefix=#{prefix}"
end

Read more in the Homebrew wiki.

1 files changed, 22 insertions, 3 deletions

diff --git a/Library/Formula/libstfl.rb b/Library/Formula/libstfl.rb
index 15603a56d..6670208a8 100644
--- a/Library/Formula/libstfl.rb
+++ b/Library/Formula/libstfl.rb
@@ -5,12 +5,31 @@ class Libstfl < Formula
   url 'http://www.clifford.at/stfl/stfl-0.22.tar.gz'
   sha1 '226488be2b33867dfb233f0fa2dde2d066e494bd'
 
+  depends_on :python => :recommended
+  depends_on 'swig'
+
   def patches; DATA; end
 
   def install
-    system "make", "install",
-                   "CC=#{ENV.cc} -pthread",
-                   "prefix=#{prefix}"
+    args = ["CC=#{ENV.cc} -pthread", "prefix=#{prefix}"]
+
+    args << "FOUND_RUBY = 0" unless MacOS::CLT.installed? # Ruby does not build on Xcode only. Help us fix this!
+
+    if build.with? 'python'
+      # Install into the site-packages in the Cellar (so uninstall works)
+      inreplace 'python/Makefile.snippet' do |s|
+        s.change_make_var! "PYTHON_SITEARCH", python.site_packages
+        s.gsub! 'lib-dynload/', ''
+      end
+      # Fails race condition of test:
+      #   ImportError: dynamic module does not define init function (init_stfl)
+      #   make: *** [python/_stfl.so] Error 1
+      ENV.deparallelize
+    else
+      args << "FOUND_PYTHON = 0"
+    end
+
+    system "make", "install", *args
   end
 end