install a gem from github

gem_from_git.rb

#!/usr/bin/env ruby -KU

require "rubygems"
require "thor"
require "tmpdir"

class GemFromGit < Thor
  include Thor::Actions

  desc "install GIT-USER/REPO", "install a gem from github source."
  method_option :tag, :default => "master", :banner => "TAG_OR_BRANCH", :aliases => '-t'
  def install(repo)
    tag = options[:tag]
    
    # http://help.rubygems.org/discussions/problems/501-broken-utf-8-handling-in-newest-rubygems-when-environment-locales-are-not-set
    ENV['LC_ALL']       = "en_US.UTF-8"
    ENV['LANG']         = "en_US.UTF-8"

    user, repo_name = repo.split('/')
    Dir.mktmpdir do |tmpdir|
      Dir.chdir tmpdir
      destination_root = tmpdir
      # get git_url
      run "wget -q #{git_url(repo,tag)}"
      run "unzip -qq #{tag}"
      gdir = Dir.glob("#{user}-#{repo_name}*").first
      Dir.chdir gdir
      gemspec = Dir.glob("*.gemspec").first
      existing_gemfiles = Dir.glob("*.gem")
      if gemspec
        if File.read(gemspec) =~ %r{\bgit\b}
          run "git init -q"
          run "git add --all"
          run "git ci -q -m 'import for gemspec'"
        end
        run "gem build #{gemspec}"
        gem_file = Dir.glob("*.gem") - existing_gemfiles
        raise Thor::Error, "no gem file was created by gem build" if gem_file.empty?
        gem_file = gem_file.first
        run "rvm current"
        run "cp #{gem_file} /tmp/"
        run "gem install #{gem_file}"
      else
        run "rake build"
        run "rake install"
      end
    end
  end
  
  private
  def git_url(repo, tag)
    raise Thor::Error, "supply repo in form 'thorsk/repo_name'" unless
      repo.split('/').length == 2
    return "https://github.com/#{repo}/zipball/#{tag}"
  end
  
end

GemFromGit.start