我在EffectiveC++中遇到了这一行:Publicmeansunencapsulated,andpracticallyspeaking,unencapsulatedmeansunchangeable,especiallyforclassesthatarewidelyused.Yetwidelyusedclassesaremostinneedofencapsulation,becausetheyaretheonesthatcanmostbenefitfromtheabilitytoreplaceoneimplementationwithabetterone作者所说的“公开的就是不封