From: Magnus Falk <magnus.falk@...>
Date: 2007-06-04T05:20:26+09:00
Subject: Building C++ with Rake

I'm familiarizing myself with Rake (and learning a spot of Ruby while
doing it) by making a build environment for a C++ project I'm doing.
I've run into a few issues though...

First off; here's the code I have so far:

require 'rake/clean'

PROJ_NAME = "testproj"
BUILD_DIR = ENV['BUILD_DIR']
OBJ_DIR = File.join(BUILD_DIR, PROJ_NAME,
File.expand_path('.').pathmap("%f"), 'objects')
SRC_FILES = FileList['src/**/*.c*']
OBJ_FILES = FileList[File.join(OBJ_DIR + '**/*.o')]

CLEAN.include(OBJ_DIR)

directory OBJ_DIR

def compileTask inclDirs, flags
  includes = inclDirs.collect { |dir| '-I' + dir + ' ' }
  compFlags = flags.collect { |flag| flag + ' ' }

  SRC_FILES.each do |srcFile|
    objFile = File.join(OBJ_DIR, srcFile.pathmap("%f").ext('o'))

    file objFile => [srcFile] do
      sh "g++ #{includes} #{compFlags} -c #{srcFile} -o #{objFile}"
    end
  end
end

def linkTask depLibDirs, depLibs, flags, target
  libDirs = depLibDirs.collect { |dir| '-L' + dir + ' ' }
  libs = depLibs.collect { |lib| '-l' + (lib[/lib(.+)\./, 1]) + ' ' }
  linkFlags = flags.collect { |flag| flag + ' ' }

  if (File.extname(target) == '.so') then
    linkFlags = linkFlags + ['-shared' + ' ']
  else
    linkFlags = linkFlags + ['-c' + ' ']
  end

  targetFile = File.join(BUILD_DIR, target)

  file targetFile => OBJ_FILES do
    objFiles = OBJ_FILES.collect { |objFile| objFile + ' ' }
    sh "g++ #{libDirs} #{libs} #{linkFlags} #{objFiles} -o
#{targetFile}"
  end
end

#----This here below I would like to have in a separate file

task :default => [:link]

task :compile => [OBJ_DIR] do
  inclDirs = ['/tmp/testdir1', '/tmp/testdir2']
  flags = ['-g', '-v']

  compileTask(inclDirs, flags)
end

task :link => [:compile] do
  target = 'libTest.so'
  depLibDirs = ['/usr/lib']
  depLibs = []
  flags = ['-fpic']

  linkTask(depLibDirs, depLibs, flags, target)
end

And my issues:

1: The file task thingy doesn't work as I thought it would, but I'm
probably using it wrong. I hope it's evident from the context what I'm
trying to do though.

2: I have lots of ugly "insert space between the arguments in my
arrays". How do I do it in a nicer way?

3: I would like to separate the "defined" tasks from the "regular"
ones so that the part furthest down is content of each "satellite"
rakefile which then includes the top part as a kind of library. But
when I tried doing it by simply putting the top part in a file and
then putting 'require "../../cppBuildLib.rb"' at the top of the
satellite file I got a message that file couldn't be found (or
something to that effect).

As I said before, I'm learning Rake and Ruby at the same time, so feel
free to point out any oddities or other stuff that could/should be
done differently.