Composite Patterns :如果想用表达 部分-整体的继承关系,组合模式一定是不二之选了
IntentComposeobjectsintotreestructurestorepresentpart-wholehierarchies.Compositeletsclientstreatindividualobjectsandcompositionsofobjectsuniformly.StructureConsequencesdefinesclasshierarchiesconsistin