- like all documentation, they are prone to code rot (going out of date)
- ideally code should be obvious; if you need a comment to explain it, perhaps it's not as simple as it could be, or perhaps we're doing something hacky that we shouldn't
Comments are often the best tool for explaining why a bit of code is formulated how it is, or explaining why a more obvious alternate implementation is a dead end.
An example of this: assume you live in a world where the formula for the circumference of a circle has not been derived. You end up deriving the formula yourself and write a function which returns 2piradius. This is as simple as it gets, not hacky at all, and you would /definitely/ want to include a comment explaining how you arrived at your weird and arbitrary-looking "3.1415" constant.
- like all documentation, they are prone to code rot (going out of date)
- ideally code should be obvious; if you need a comment to explain it, perhaps it's not as simple as it could be, or perhaps we're doing something hacky that we shouldn't