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Diffstat (limited to 'Library/Homebrew/python_helper.rb')
| -rw-r--r-- | Library/Homebrew/python_helper.rb | 80 |
1 files changed, 80 insertions, 0 deletions
diff --git a/Library/Homebrew/python_helper.rb b/Library/Homebrew/python_helper.rb new file mode 100644 index 000000000..ef71b2a30 --- /dev/null +++ b/Library/Homebrew/python_helper.rb @@ -0,0 +1,80 @@ + +# 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) + else + true + end + end + + # 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? + puts "brew: Python block (#{py.binary})..." if ARGV.verbose? + 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: Setting 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? + # 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 + end + else + puts "brew: Using #{py.binary}" if ARGV.verbose? + # We return here with intention, because no block_given? + return py + end + end + end +end |