I've had the opposite experience trying to get python and/or ruby not to trash my global environment and various things wanting the system to be setup for their

I've had the opposite experience trying to get python and/or ruby not to trash my global environment and various things wanting the system to be setup for their versions and libraries. I like that NPM by default makes all dependencies local and npm lets you include your dev dependencies local to that project. Note: I know their are magic incantations for python and ruby to get them to make everything project local but they aren't what python and ruby do by default.