Software Design

State Pattern: Clean Order Lifecycles

UML Class Diagrams · made in Skemio

UML class diagram showing an Order class holding an OrderState interface, implemented by PendingState, PaidState, and ShippedState.
UML class diagram showing an Order class holding an OrderState interface, implemented by PendingState, PaidState, and ShippedState.

What it shows

  • Encapsulate state-specific logic into dedicated classes to kill branching.
  • Transitions become explicit methods, preventing invalid lifecycle jumps.
  • Add new lifecycle steps like Refunded without touching existing states.

The takeaway

Replace nested conditionals with state objects to keep workflow logic modular and strictly validated.

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