Behavioral patterns

Build validation and request-processing pipelines with small handlers composed through interfaces.

Encapsulate operations for queuing, audit history, and undo/redo while keeping Go error handling explicit.

Define a small grammar for recurring business rules and evaluate sentences of that grammar with an expression tree.

Traverse a collection without exposing its internal representation, keeping traversal state separate from the aggregate.

Centralize communication between collaborating objects so they depend on a coordinator instead of referencing each other directly.

Capture and restore object state without exposing internal details so undo and rollback remain explicit and controlled.

Notify dependent subscribers when state changes so event-driven reactions stay decoupled from the publisher.

Change an object’s behavior when its internal state changes by delegating transitions and rules to state-specific types.

Encapsulate interchangeable algorithms behind one interface so callers can swap behavior without branching on concrete rules.

Define the skeleton of an algorithm once while letting concrete steps vary through narrow hook methods.

Add operations across a stable object structure without changing each node type whenever a new operation is introduced.