Show RAILS version using zsh RPROMPT.

rails_version_rprompt.sh

_set_env_git_current_branch() {
  GIT_CURRENT_BRANCH=$( git branch &> /dev/null | grep '^\*' | cut -b 3- )
}
_set_env_rails_version() {
  RAILS_VERSION=$( rails -v &> /dev/null | cut -b 7- )
}

_update_rprompt () {
  if [ "`git ls-files 2>/dev/null`" ]; then
    RPROMPT="[$RAILS_VERSION:%2.:$GIT_CURRENT_BRANCH]"
  else
    RPROMPT="[$RAILS_VERSION:%2.]"
  fi
}

precmd()
{
  _set_host_and_pwd_on_title
  _set_env_git_current_branch
  _set_env_rails_version
  _update_rprompt
}