This is the second post in a series about the Four Rules of Simple Design. “No duplication” means that when a domain concept is represented in two or more places in the code, you adjust the code so that that domain concept is represented in just one place. This usually involves putting shared data or logic in a single shared place so they can be accessed from wherever they’re needed. Why no duplication? Consider a user account record. Say there are multiple conditions that determine whe...
