Oh that's nice. When I last looked (quite a long time ago), local::lib seemed to be the recommended way, and that seemed a bit more fiddly than python's virtualenv.

Carton uses local::lib under the covers. I found local::lib far less fiddly than virtualenv myself, but it just doesn't try to do as much as virtualenv. These days I do PHP for a living, and for all the awfulness in php, they did nail it with composer.