重构 -- Replace Subclass with Fields（以值域取代子类）

来源：互联网发布：node.js 数据库编辑：程序博客网时间：2024/05/29 08:07

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 abstract class Person
{
   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

public class Person
{
    privatebool _IsMale;
    privatestring _Code;
 
    publicbool IsMale
    {
        get{ return _IsMale; }
        set{ _IsMale = value; }
    }
 
    publicstring Code
    {
        get{ return _Code; }
        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")
    { }
}

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