elixir-build exenv formula

elixir-build.rb

require 'formula'

class ElixirBuild < Formula
  homepage 'https://github.com/mururu/elixir-build'
  url 'https://github.com/mururu/elixir-build/tarball/v20121112'
  sha1 '6d3ae172359e26ee94370ce309edad79c996ea78'

  head 'https://github.com/mururu/elixir-build.git'

  option "without-exenv", "Don't install as an exenv plugin"

  depends_on 'exenv' unless build.include? 'without-exenv'

  def install
    ENV['PREFIX'] = prefix
    system "./install.sh"

    exenv_plugins = "#{HOMEBREW_PREFIX}/var/lib/exenv/plugins"
    mkdir_p exenv_plugins
    ln_sf opt_prefix, "#{exenv_plugins}/#{name}" unless build.include? 'without-exenv'
  end
end