class Gem::Tasks::SCM::Status

def define
  namespace :scm do
    task :status do
      status = self.status
      unless status.strip.empty?
        error "Project has uncommitted changes!"
        puts status
        abort
      end
    end
  end
  # do not allow tagging releases when the repository is dirty
  task 'scm:tag' => 'scm:status'
  # do not allow pushing commits when the repository is dirty
  task 'scm:push' => 'scm:status'
  # do not allow building packages when the repository is dirty
  task :build => 'scm:status'
  # do not allow pushing gems when the repository is dirty
  task :push => 'scm:status'
end

def initialize(options={})
  super()
  yield self if block_given?
  define
end

def status
  case @project.scm
  when :git then `git status --short --untracked-files=no`
  when :hg  then `hg status --quiet`
  when :svn then `svn status --quiet`
  else            ''
  end
end