The principle that any given piece of knowledge or business logic should exist in exactly one place in a system, so that changes propagate consistently without the risk of contradiction.
Rolf used a value-added tax example: extracting the tax calculation into one named method means legislation changes require an update in one location only. Simon noted this connects to a quote from Robert C. Martin: "Truth can only be found in one place: the code." A system with a single point of truth for its logic is easier to maintain, test, and reason about.
Rolf used a value-added tax example: extracting the tax calculation into one named method means legislation changes require an update in one location only. Simon noted this connects to a quote from Robert C. Martin: "Truth can only be found in one place: the code." A system with a single point of truth for its logic is easier to maintain, test, and reason about.
