golang env for .bash_profile

MAIN_GOPATH=/usr/local/Cellar/go/1.2/workspace
export GOPATH=$MAIN_GOPATH
MAIN_PATH=$PATH:$GOPATH/bin
export PATH=$MAIN_PATH

# goenv functions
activate(){
  export GOPATH="$(cd "$(dirname "${BASH_SOURCE[0]}" )" && pwd)"
  export OLDPS1=$PS1
  export PS1="(go:$(basename $GOPATH)) $PS1"
  mkdir -p $GOPATH/bin
  mkdir -p $GOPATH/pkg
  mkdir -p $GOPATH/src/$(basename $GOPATH)
  export PATH=$GOPATH/bin:$PATH
  alias gcd="cd $GOPATH/src/$(basename $GOPATH)"

  deactivate() {
    echo "Goodbye! =)"
    cd $GOPATH
    echo "Now, you in \`$(pwd)\` directory."
    export PS1=$OLDPS1
    export GOPATH=$MAIN_GOPATH
    export PATH=$MAIN_PATH
    unset OLDPS1
    unalias gcd
    unset deactivate
  }
}