Jacob Carlborg put together a guest post describing the history and implementation of D Version manager. If you've never heard of it, take a look. It's a useful utility to have installed.

Blog:
https://dlang.org/blog/2016/08/17/inside-d-version-manager/

Reddit:
https://www.reddit.com/r/programming/comments/4y58kc/inside_d_version_manager/