Set GOPATH and PATH if .goworkspace present

example

$ echo $GOPATH

$ echo $PATH
/bin:/usr/bin:/usr/local/bin
$ mkdir -p /tmp/some_project
$ touch /tmp/some_project/.goworkspace
$ cd /tmp/some_project
$ echo $GOPATH
/tmp/some_project
$ echo $PATH
/bin:/usr/bin:/usr/local/bin:/tmp/some_project/bin
$ cd ~
$ echo $GOPATH

$ echo $PATH
/bin:/usr/bin:/usr/local/bin

profile

function remove_from_path() {
  local readonly remove=$1
  local work=:$PATH:
  work=${work/:$remove:/:}
  work=${work#:}
  work=${work%:}
  export PATH=$work
}

function go_env_auto() {
  local current_dir="$PWD"

  until [[ -z "$current_dir" ]]; do
    if [[ -f "$current_dir/.goworkspace" ]]; then
      [[ "$GOPATH_AUTO" == "$current_dir" ]] && return

      GOPATH_AUTO=$current_dir
      export GOPATH=$current_dir
      export PATH=$PATH:$GOPATH/bin
      return
    fi

    current_dir="${current_dir%/*}"
  done

  if [[ -n "$GOPATH_AUTO" ]]; then
    [[ -n "$GOPATH" ]] && remove_from_path $GOPATH/bin
    unset GOPATH_AUTO
    unset GOPATH
  fi
}

if [[ -n "$ZSH_VERSION" ]]; then
  if [[ ! "$preexec_functions" == *go_env_auto* ]]; then
    preexec_functions+=("go_env_auto")
  fi
elif [[ -n "$BASH_VERSION" ]]; then
  trap '[[ "$BASH_COMMAND" != "$PROMPT_COMMAND" ]] && go_env_auto' DEBUG
fi