Code templating

A template is an abstraction over things that do not exist yet, which makes it the easiest kind of abstraction to get wrong. Two costs are usually underestimated: templates rot silently while their generated children live on, and a wrong parameterisation is worse than copy-paste, because everyone inherits it.

The honest bar: three real instances before you templatize. Two examples cannot tell you what varies — with two, every difference looks essential and every similarity looks universal. The third instance is what separates them.

1. Lay the real instances side by side

Diff them. Literally, not from memory:

diff -ru project-a/ project-b/ | head -100