depends_on :python sets PYTHONPATH internally

This applies only to non-brewed python:
The user will still have to set his PYTHONPATH
in order to import python modules in an
external python interpreter. However, a
warning will be displayed, now.

Further, during the build, the PYTHONPATH
will be set to Homebrew's global site-packages
so that software (like PyQt and others) that
need to `import sipconfig` in python can
find the brewed sip and its python module.

2 files changed, 13 insertions, 3 deletions

diff --git a/Library/Homebrew/python_helper.rb b/Library/Homebrew/python_helper.rb
index 992ef43c1..5f74b627d 100644
--- a/Library/Homebrew/python_helper.rb
+++ b/Library/Homebrew/python_helper.rb
@@ -57,7 +57,7 @@ def python_helper(options={:allowed_major_versions => [2, 3]}, &block)
           # In order to install into the Cellar, the dir must exist and be in the
           # PYTHONPATH. This will be executed in the context of the formula
           # so that lib points to the HOMEBREW_PREFIX/Cellar/<formula>/<version>/lib
-          puts "brew: Setting PYTHONPATH=#{py.site_packages}" if ARGV.verbose?
+          puts "brew: Appending to PYTHONPATH: #{py.site_packages}" if ARGV.verbose?
           mkdir_p py.site_packages
           ENV.append 'PYTHONPATH', py.site_packages, ':'
           ENV['PYTHON'] = py.binary
diff --git a/Library/Homebrew/requirements/python_dependency.rb b/Library/Homebrew/requirements/python_dependency.rb
index 7b86b34a9..962b111d2 100644
--- a/Library/Homebrew/requirements/python_dependency.rb
+++ b/Library/Homebrew/requirements/python_dependency.rb
@@ -61,7 +61,7 @@ class PythonInstalled < Requirement
   # We look for a brewed python or an external Python and store the loc of
   # that binary for later usage. (See Formula#python)
   satisfy :build_env => false do
-    @unsatisfied_because = "This formula needs #{@name}.\n"
+    @unsatisfied_because = ''
     if binary.nil?
       @unsatisfied_because += "But no `#{@name}` found in your PATH! Consider to `brew install #{@name}`."
       false
@@ -76,8 +76,17 @@ class PythonInstalled < Requirement
       false
     elsif @min_version.major == 2 && `python -c "import sys; print(sys.version_info[0])"`.strip == "3"
       @unsatisfied_because += "Your `python` points to a Python 3.x. This is not supported."
-      false
     else
+      # If everything satisfied, we check the PYTHONPATH, that has to be set for non-brewed Python
+      if !brewed? && (ENV['PYTHONPATH'].nil? || !ENV['PYTHONPATH'].include?(global_site_packages)) then
+        opoo <<-EOS.undent
+          For non-brewed Python, you have to set the PYTHONPATH in order to
+          find brewed Python modules.
+            export PYTHONPATH=#{global_site_packages}:$PYTHONPATH
+        EOS
+        # This is just to shut up a second run of satisfy.
+        ENV['PYTHONPATH'] = global_site_packages.to_s
+      end
       true
     end
   end
@@ -215,6 +224,7 @@ class PythonInstalled < Requirement
 
     ENV['PYTHONHOME'] = nil  # to avoid fuck-ups.
     ENV['PYTHONNOUSERSITE'] = '1'
+    ENV['PYTHONPATH'] = global_site_packages.to_s unless brewed?
     # Python respects the ARCHFLAGS var if set. Shall we set them here?
     # ENV['ARCHFLAGS'] = ??? # FIXME
     ENV.append 'CMAKE_INCLUDE_PATH', incdir, ':'