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, 3 insertions, 1 deletions

diff --git a/Library/Formula/git.rb b/Library/Formula/git.rb
index 73ca95113..18e909d04 100644
--- a/Library/Formula/git.rb
+++ b/Library/Formula/git.rb
@@ -20,6 +20,7 @@ class Git < Formula
   option 'with-blk-sha1', 'Compile with the block-optimized SHA1 implementation'
   option 'without-completions', 'Disable bash/zsh completions from "contrib" directory'
 
+  depends_on :python
   depends_on 'pcre' => :optional
   depends_on 'gettext' => :optional
 
@@ -29,8 +30,9 @@ class Git < Formula
     ENV['NO_DARWIN_PORTS'] = '1'
     ENV['V'] = '1' # build verbosely
     ENV['NO_R_TO_GCC_LINKER'] = '1' # pass arguments to LD correctly
+
     ENV['PERL_PATH'] = which 'perl' # workaround for users of perlbrew
-    ENV['PYTHON_PATH'] = which 'python' # python can be brewed or unbrewed
+    ENV['PYTHON_PATH'] = python.binary if python
 
     # Clean XCode 4.x installs don't include Perl MakeMaker
     ENV['NO_PERL_MAKEMAKER'] = '1' if MacOS.version >= :lion