动机（Motivation）
修改这些函数，使它们返回superclass中的某个（新增值域，然后销毁subclasses）
示例
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public class { public abstract boolIsMale(); public abstract stringGetCode(); publicPerson CreateMale() { returnnew Male(); } publicPerson CreateFemale() { returnnew Female(); }}publicclass Male : Person{ publicoverride boolIsMale() { returntrue; } publicoverride stringGetCode() { return"M"; }}publicclass Female : Person{ publicoverride boolIsMale() { returnfalse; } publicoverride stringGetCode() { return"F"; }} |
改为
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public Person{ privatebool _IsMale; privatestring _Code; publicbool IsMale { get{ return set{ _IsMale = value; } } publicstring Code { get{ return set{ _Code = value; } } publicPerson(boolisMale, stringcode) { this._IsMale = isMale; this._Code = code; }}publicclass Male : Person{ publicMale() :base(true,"M") { }}publicclass Female : Person{ publicFemale() :base(false,"F") { }} |