From: Mauricio Fernandez <mfp@...>
Date: 2006-05-24T05:35:23+09:00
Subject: Re: [ANN] rcov 0.4.0 (code coverage) - scriptability, accuracy, unrotten internals

On Tue, May 23, 2006 at 07:32:41AM +0900, John-Mason P. Shackelford wrote:
> I was recently faced with the issue of packaging a library that needed
> to execute cross platform but for which a windows binary was required
> and wondered why, when a win32 library is required, we don't just
> package it in a win32 directory inside the gem and require it when the
> platform is win32. These binaries take up very little disk space
> (which is cheap anyway) and I'd rather have a little unused windows
> dll on my Linux systems than to bother with installing (and
> maintaining) different gems for different platforms.
> 
> Okay, Jim, tell me I am crazy. (Or ignorant--that would be much worse.)

I got to generate the platform-independent package and the cross-compiled
binary one as follows:


PKG_REVISION = ".1"
PKG_FILES = FileList[
# sources, docs and Rakefile
# this is a modified rbconfig.rb based on that generated by a cross-compiled
# ruby targetting mingw32
"mingw-rbconfig.rb" 
]

require 'rake/gempackagetask'
Spec = Gem::Specification.new do |s|
  # ...
  s.files = PKG_FILES.to_a
  s.extensions << "ext/rcovrt/extconf.rb"
  # ...
end

task :gem => [:test]
Rake::GemPackageTask.new(Spec) do |p|
  p.need_tar = true
end

# {{{ Cross-compilation and building of a binary RubyGems package for mswin32

require 'rake/clean'

WIN32_PKG_DIR = "rcov-" + Rcov::VERSION + PKG_REVISION

file "#{WIN32_PKG_DIR}" => [:package] do
  sh "tar zxf pkg/#{WIN32_PKG_DIR}.tgz"
end

# this overrides the normal rbconfig.rb, in order to generate a Makefile
# suitable for cross-compilation
desc "Cross-compile the rcovrt.so extension for win32"
file "rcovrt_win32" => ["#{WIN32_PKG_DIR}"] do
  cp "mingw-rbconfig.rb", "#{WIN32_PKG_DIR}/ext/rcovrt/rbconfig.rb"
  sh "cd #{WIN32_PKG_DIR}/ext/rcovrt/ && ruby -I. extconf.rb && make"
  mv "#{WIN32_PKG_DIR}/ext/rcovrt/rcovrt.so", "#{WIN32_PKG_DIR}/lib"
end

# New spec, essentially like the first one, modulo:
# * the platform, set to WIN32,
# * the removal of the extensions attribute, so that no compilation is
#   attempted at install time
# * the addition of the desired .so to the list of files to be included

Win32Spec = Spec.clone
Win32Spec.platform = Gem::Platform::WIN32
Win32Spec.extensions = []
Win32Spec.files += ["lib/rcovrt.so"]

desc "Build the binary RubyGems package for win32"
task :rubygems_win32 => ["rcovrt_win32"] do
  Dir.chdir("#{WIN32_PKG_DIR}") do
    Gem::Builder.new(Win32Spec).build
    verbose(true) {
      mv Dir["*.gem"].first, "../pkg/rcov-#{Rcov::VERSION + PKG_REVISION}-mswin32.gem"
    }
  end
end

CLEAN.include "#{WIN32_PKG_DIR}"

-- 
Mauricio Fernandez  -   http://eigenclass.org   -  singular Ruby