Support for multiple GOPATHs - set GOPATH on change of directory

.bashrc

# with these functions you can have multiple gopath directories residing in /opt, where each gopath folder starts with "go-"
# when cd-ing to one of these directories (or any directory in them, on any level) the GOPATH gets changed automagically

function cd {
    # call builtin cd. change to the new directory
    builtin cd $@
    # call a hook function that can use the new working directory
    # to decide what to do
    set_gopath
}

# gopath changer
function set_gopath {
    pwd=$(pwd)
    
    if [[ "$pwd/" =~ ^/opt/go- ]] ; then
        gopath_local=$(echo $pwd| cut -d'/' -f 1,2,3)
        if [ "$GOPATH" != "$gopath_local" ] ; then
            GOPATH=$gopath_local
            export GOPATH
            echo "GOPATH set to $GOPATH"
        fi
    fi
}