[virtualenvwrapper] automatic workon hook on cd

cd_hook.sh

export PROJECTS_HOME="$HOME/Projects"

function has_virtualenv__() {
  if [[ ${PWD##$PROJECTS_HOME} != $PWD ]]; then
    IFS="/" read -ra ADDR <<< "${PWD##$PROJECTS_HOME}"
    venvname=${ADDR[1]}
    cur_env=${VIRTUAL_ENV##$WORKON_HOME}
    if [[ $venvname != "" ]] && [[ -d "$WORKON_HOME/$venvname" ]]; then
      if [[ ${cur_env:1} != $venvname ]]; then
        workon "$venvname"
      fi
    else
      if [[ $VIRTUAL_ENV != "" ]]; then
        deactivate
      fi
    fi
  else
    if [[ $VIRTUAL_ENV != "" ]]; then
      deactivate
    fi
  fi
}

function venv_cd() {
  builtin cd "$@" && has_virtualenv__
}

alias cd=venv_cd

@euphoris virtualenvwrapper have hooks http://virtualenvwrapper.readthedocs.org/en/latest/scripts.html

@juanpabloaj that only allows you to cd on workon, but not to workon on cd.

@euphoris with ZSH, you can define a chpwd function that will be called on each working directory change. Also note that read -a is a GNU extension which does not work out of the box on OS X and BSD. I used echo "${PWD##$PROJECTS_HOME}" | cut -d'/' -f2) instead.