PythonInstalled: Don't require superenv

* The python do ... end block does no longer
  require 'superenv' but saves and restores
  the ENV by using ENV.to_hash and `ensure`.
  This should resolve some build problems
  with formulae using `env :std`!
* `python_helper` is now in a module `Python`.
* Imporoved some comments in python_dependency.rb

3 files changed, 77 insertions, 72 deletions

diff --git a/Library/Homebrew/formula.rb b/Library/Homebrew/formula.rb
index ead132bbf..cf88bd3be 100644
--- a/Library/Homebrew/formula.rb
+++ b/Library/Homebrew/formula.rb
@@ -307,7 +307,7 @@ class Formula
 
   def python(options={:allowed_major_versions => [2, 3]}, &block)
     require 'python_helper'
-    python_helper(options, &block)
+    Python::python_helper(options, &block)
   end
 
   # Explicitly only execute the block for 2.x (if a python 2.x is available)
diff --git a/Library/Homebrew/python_helper.rb b/Library/Homebrew/python_helper.rb
index 5f74b627d..4bc50907c 100644
--- a/Library/Homebrew/python_helper.rb
+++ b/Library/Homebrew/python_helper.rb
@@ -2,78 +2,83 @@
 # The python_helper is used in the Formula class when the user calls
 # `python`, `python2` or `python3`.
 
-# This method has a dual nature. For one, it takes a &block and sets up
-# the ENV such that a Python, as defined in the requirements, is the default.
-# If there are multiple `PythonInstalled` requirements, the block is evaluated
-# once for each Python. This makes it possible to easily support 2.x and
-# 3.x Python bindings without code duplication in formulae.
-# If you need to special case stuff, set :allowed_major_versions.
-# Second, inside the block, a formula author may call this method to access
-# certain convienience methods for the currently selected Python, e.g.
-# `python.site_packages`.
-def python_helper(options={:allowed_major_versions => [2, 3]}, &block)
-  if !block_given? and !@current_python.nil?
-    # We are already inside of a `python do ... end` block, so just return
-    # the current_python or false if the version.major is not allowed.
-    if options[:allowed_major_versions].include?(@current_python.version.major)
-      @current_python
-    else
-      false
-    end
-  else
-    # Look for PythonInstalled requirements for this formula
-    python_reqs = requirements.select{ |r| r.kind_of?(PythonInstalled) }
-    if python_reqs.empty?
-      raise "If you use python in the formula, you have to add `depends_on :python` (or :python3)!"
-    end
-    # Now select those that are satisfied and matching the version.major
-    python_reqs = python_reqs.select do |p|
-      p.satisfied? &&
-      options[:allowed_major_versions].include?(p.version.major) &&
-      if p.optional? || p.recommended?
-        self.build.with?(p.name)
+module Python
+  # This method has a dual nature. For one, it takes a &block and sets up
+  # the ENV such that a Python, as defined in the requirements, is the default.
+  # If there are multiple `PythonInstalled` requirements, the block is evaluated
+  # once for each Python. This makes it possible to easily support 2.x and
+  # 3.x Python bindings without code duplication in formulae.
+  # If you need to special case stuff, set :allowed_major_versions.
+  # Second, inside the block, a formula author may call this method to access
+  # certain convienience methods for the currently selected Python, e.g.
+  # `python.site_packages`.
+  def python_helper(options={:allowed_major_versions => [2, 3]}, &block)
+    if !block_given? and !@current_python.nil?
+      # We are already inside of a `python do ... end` block, so just return
+      # the current_python or false if the version.major is not allowed.
+      if options[:allowed_major_versions].include?(@current_python.version.major)
+        @current_python
       else
-        true
+        false
+      end
+    else
+      # Look for PythonInstalled requirements for this formula
+      python_reqs = requirements.select{ |r| r.kind_of?(PythonInstalled) }
+      if python_reqs.empty?
+        raise "If you use python in the formula, you have to add `depends_on :python` (or :python3)!"
+      end
+      # Now select those that are satisfied and matching the version.major
+      python_reqs = python_reqs.select do |p|
+        p.satisfied? &&
+        options[:allowed_major_versions].include?(p.version.major) &&
+        if p.optional? || p.recommended?
+          self.build.with?(p.name)
+        else
+          true
+        end
       end
-    end
 
-    # Allow to use an else-branch like so: `if python do ... end; else ... end`
-    return false if python_reqs.empty?
+      # Allow to use an else-branch like so: `if python do ... end; else ... end`
+      return false if python_reqs.empty?
 
-    # Sort by version, so the older 2.x will be used first and if no
-    # block_given? then 2.x is preferred because it is returned.
-    # Further note, having 3.x last allows us to run `2to3 --write .`
-    # which modifies the sources in-place (for some packages that need this).
-    python_reqs.sort_by{ |py| py.version }.map do |py|
-      # Now is the time to set the site_packages to the correct value
-      py.site_packages = lib/py.xy/'site-packages'
-      if !block_given?
-        return py
-      else
-        puts "brew: Python block (#{py.binary})..." if ARGV.verbose? && ARGV.debug?
-        require 'superenv'
-        # Ensure env changes are only temporary by using `with_build_environment`
-        ENV.with_build_environment do
-          # 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: Appending to PYTHONPATH: #{py.site_packages}" if ARGV.verbose?
-          mkdir_p py.site_packages
-          ENV.append 'PYTHONPATH', py.site_packages, ':'
-          ENV['PYTHON'] = py.binary
-          ENV.prepend 'CMAKE_INCLUDE_PATH', py.incdir, ':'
-          ENV.prepend 'PKG_CONFIG_PATH', py.pkg_config_path, ':' if py.pkg_config_path
-          ENV.prepend 'PATH', py.binary.dirname, ':' unless py.from_osx?
-          ENV.prepend 'LDFLAGS', "-F#{py.framework}" if py.brewed?
-          # Track the state of the currently selected python for this block,
-          # so if this python_helper is called again _inside_ the block, we can
-          # just return the right python (see `else`-branch a few lines down):
-          @current_python = py
-          res = instance_eval(&block)
-          @current_python = nil
-          res
+      # Sort by version, so the older 2.x will be used first and if no
+      # block_given? then 2.x is preferred because it is returned.
+      # Further note, having 3.x last allows us to run `2to3 --write .`
+      # which modifies the sources in-place (for some packages that need this).
+      python_reqs.sort_by{ |py| py.version }.map do |py|
+        # Now is the time to set the site_packages to the correct value
+        py.site_packages = lib/py.xy/'site-packages'
+        if !block_given?
+          return py
+        else
+          puts "brew: Python block (#{py.binary})..." if ARGV.verbose? && ARGV.debug?
+          # Ensure env changes are only temporary
+          begin
+            old_env = ENV.to_hash
+            # 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: Appending to PYTHONPATH: #{py.site_packages}" if ARGV.verbose?
+            mkdir_p py.site_packages
+            ENV.append 'PYTHONPATH', py.site_packages, ':'
+            ENV['PYTHON'] = py.binary
+            ENV.prepend 'CMAKE_INCLUDE_PATH', py.incdir, ':'
+            ENV.prepend 'PKG_CONFIG_PATH', py.pkg_config_path, ':' if py.pkg_config_path
+            ENV.prepend 'PATH', py.binary.dirname, ':' unless py.from_osx?
+            ENV.prepend 'LDFLAGS', "-F#{py.framework}" if py.brewed?
+            # Track the state of the currently selected python for this block,
+            # so if this python_helper is called again _inside_ the block, we can
+            # just return the right python (see `else`-branch a few lines down):
+            @current_python = py
+            res = instance_eval(&block)
+            @current_python = nil
+            res
+          ensure
+            ENV.replace(old_env)
+          end
         end
       end
     end
-  end
-end
+  end  # enf of python_helper method
+
+end
\ No newline at end of file
diff --git a/Library/Homebrew/requirements/python_dependency.rb b/Library/Homebrew/requirements/python_dependency.rb
index 962b111d2..74bf1a1a8 100644
--- a/Library/Homebrew/requirements/python_dependency.rb
+++ b/Library/Homebrew/requirements/python_dependency.rb
@@ -128,8 +128,8 @@ class PythonInstalled < Requirement
     "python#{version.major}.#{version.minor}"
   end
 
-  # Homebrew's global site-packages. The local ones are populated by the
-  # python_helper method when the `prefix` of a formula is known.
+  # Homebrew's global site-packages. The local ones (just `site_packages`) are
+  # populated by the python_helper method when the `prefix` of a formula is known.
   def global_site_packages
     HOMEBREW_PREFIX/"lib/#{xy}/site-packages"
   end
@@ -230,7 +230,7 @@ class PythonInstalled < Requirement
     ENV.append 'CMAKE_INCLUDE_PATH', incdir, ':'
     ENV.append 'PKG_CONFIG_PATH', pkg_config_path, ':' if pkg_config_path
     # We don't set the -F#{framework} here, because if Python 2.x and 3.x are
-    # used, `Python.framework` is ambuig. However, in the `python do` block
+    # used, `Python.framework` is ambiguous. However, in the `python do` block
     # we can set LDFLAGS+="-F#{framework}" because only one is temporarily set.
 
     # Udpate distutils.cfg (later we can remove this, but people still have