Summary

Pattern Comparison

Pattern	When to Apply	Strengths	Caveats	Common Use Cases
Strategy	Conditional branching	High flexibility and testability	Can lead to many small classes	Discount processing, algorithm switching
State	When state transitions are involved	Clear state separation	Overkill if states are minimal	UI modes, business workflows
Command	When command history is needed	Supports Undo/Redo	Command objects may proliferate	Text editors, operation tracking
Chain of Responsibility	Linear flow of conditional logic	Great separation and extensibility	Risk of unhandled cases	Validation, middleware chains
Interpreter	Complex, configurable conditions	Extracts logic as external rules	Can become complex to implement	Rule engines, DSLs, search expressions

Choosing the Right Pattern

• Use Strategy for simple condition-based behavior switching
• Choose State when the logic depends on internal state transitions
• Apply Command to encapsulate operations and enable reusability
• Use Chain of Responsibility when you want to process handlers in sequence
• Go with Interpreter when conditions are dynamic and rule-based

Team Discussion Snippets

• “This condition block looks messy—let’s extract it into a Strategy so it’s easier to test.”
• “Since the behavior depends on state, wouldn’t a State pattern make things clearer?”
• “We’re repeating similar logic—why not wrap it as Command and add undo support?”
• “These checks feel sequential—maybe a Chain of Responsibility fits better here?”
• “If the logic flow is fixed, chaining handlers sounds ideal using Chain of Responsibility.”
• “This if-tree could be declared as rules—we might want to implement an Interpreter here.”