Tell Don’t Ask

← Back to Other Design Principles

Command objects, don’t interrogate them. Rather than asking an object for data and acting on it, tell the object what to do. This keeps behavior with the data it operates on, maintaining encapsulation.

Key Properties

• Command Over Query
• Behavior Locality

Related

• Encapsulation (preserved by TDA)
• Law of Demeter (related principle)

---

design-principles tell-dont-ask