Command–query separation

Command-Query Separation (CQS) is a programming principle that states that a method should either be a command that performs an action or a query that returns data, but not both. This principle helps to maintain a clear distinction between actions that change the state of a system and those that retrieve information about the system's state. ### Key Aspects of CQS: 1. **Commands**: These are methods that perform operations that modify the state of an object or system.