brew/Library/Homebrew/python_helper.rb
2013-09-14 12:21:49 +01:00

91 lines
4.3 KiB
Ruby

# This helper method 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 `PythonDependency` 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`.
# This method should be executed in the context of the formula, so that
# prefix is defined. Note, that this method will set @current_python to be
# able to refer to the current python if a block is executed for 2.x and 3.x.
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 nil if the version.major is not allowed.
if options[:allowed_major_versions].include?(@current_python.version.major)
return @current_python
else
return nil
end
end
# Look for PythonDependency requirements for this formula:
python_reqs = requirements.select{ |r| r.kind_of?(PythonDependency) }
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 and
# check that no two python binaries are the same (which could be the case
# because more than one `depends_on :python => 'module_name' may be present).
filtered_python_reqs = []
python_reqs.each do |py|
next if filtered_python_reqs.any? { |req| req.binary == py.binary }
next unless py.satisfied?
next unless options[:allowed_major_versions].include?(py.version.major)
next if (py.optional? || py.recommended?) && build.without?(py.name)
filtered_python_reqs << py
end
# Allow to use an else-branch like so: `if python do ... end; else ... end`.
return nil if filtered_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).
filtered_python_reqs.sort_by{ |py| py.version }.map do |py|
# Now is the time to `site_packages` to the correct value in the Cellar.
py.site_packages = lib/py.xy/'site-packages'
py.private_site_packages = libexec/"lib"/py.xy/"site-packages"
return py if !block_given?
puts "brew: Python block (#{py.binary})..." if ARGV.verbose? && ARGV.debug?
# Ensure env changes are only temporary:
old_env = ENV.to_hash
begin
# 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 and
# lib points to the `HOMEBREW_PREFIX/Cellar/<formula>/<version>/lib`.
mkdir_p py.site_packages
ENV.append_path 'PYTHONPATH', py.site_packages
# Allow to --prefix=libexec if a private site-packages is needed.
mkdir_p py.private_site_packages
ENV.append_path 'PYTHONPATH', py.private_site_packages
puts "brew: PYTHONPATH=#{ENV['PYTHONPATH']}" if ARGV.verbose?
ENV['PYTHON'] = py.binary
ENV.prepend_path 'CMAKE_INCLUDE_PATH', py.incdir
ENV.prepend_path 'PKG_CONFIG_PATH', py.pkg_config_path if py.pkg_config_path
ENV.prepend_path 'PATH', py.binary.dirname unless py.from_osx?
#Note: Don't set LDFLAGS to point to the Python.framework, because
# it breaks builds (for example scipy.)
# 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.
@current_python = py
res = instance_eval(&block)
@current_python = nil
res
ensure
# Clean up if the private_site_packages has not been used.
py.private_site_packages.rmdir if py.private_site_packages.children.empty?
ENV.replace(old_env)
end
end
end