How should people enroll in classes?

Students can be:

sent a link, where they log in and the link will do it for them (lame)
select from a list of classes and self-enroll (not necessarily secure but that doesn't really matter)
- self-enroll with professor approval (I like this option the best at the moment)
be pulled from canvas (causes questions in linking up canvas accounts with DERP accounts, but possible)

nasonfish / derp