Summary

Pattern Comparison

Pattern	When to Apply	Strengths	Caveats	Common Use Cases
State	When behavior varies based on internal state	Clear separation of responsibilities and transitions	Can be overkill with few states	Step flows, workflows, UI mode switching
Strategy	When behavior changes based on external input	Easy to swap logic	State transition logic handled elsewhere	Algorithm switching, discount strategies
Command	When focusing on operations, not states	Easy to manage execution history, Undo/Redo	Not ideal for state transitions	Batch processing, queues, operation logs

Choosing the Right Pattern

• If conditionals increase based on internal state → consider State
• If you only need to swap behavior without transitions → use Strategy
• If the focus is on actions and their history → Command is a better fit

Team Discussion Snippets

• “This behavior changes with state—let’s extract it using the State pattern to improve testability.”
• “We’re just switching logic based on inputs—Strategy might be a cleaner choice.”
• “Since we’re more focused on command execution and history, Command could be a better abstraction.”