有没有一种方法可以通过类的层次结构来分配属性？

Question

请参阅类的以下层次结构：

Person [age, country, hair color, eyes color..]
   Adult [job, car..]
      Man [favorite beer..]
      Woman [purse..]
   Child [school, favorite toy]
      Boy
      Girl [doll]

每个派生的类都有特定的属性：例如，成年人可能有工作，但 child 没有。一个女孩可能有一个最喜欢的洋娃娃和一个学校的名字。一个男孩也有学校名字，但他没有喜欢的娃娃。

我想实现一个克隆 Boy 的方法（返回具有完全相同属性的 Boy object）。我不想返回 Boy 并手动设置从 Child 和 Person 继承的所有属性，而是想避免这种情况。

注意：Child、Adult和Person是抽象的类。

注意2：所有这些人都有我不想复制的复杂引用，在某些情况下我只想复制那些引用的ID，但这应该手动完成，所以我需要一些控制克隆 objects.

我想到了 Person 中的一个虚方法，它在每个子类中都被重写了，但是由于 Person 无法实例化，我不确定如何实现这种行为。

Answer 1

MemberwiseClone() 方法可能就是您要找的方法：https://msdn.microsoft.com/en-us/library/system.object.memberwiseclone(v=vs.110).aspx

请注意，您需要手动克隆 class 的所有引用类型成员，因为上述函数只会克隆它们的引用，而生成的 Boy 克隆成员将引用与那些成员的原创。

如果您的大部分或所有成员都是引用类型，ICloneable 是更可靠的解决方案：https://msdn.microsoft.com/en-us/library/system.icloneable(v=vs.110).aspx

Answer 2

无需沿着路径 shallow/deep 克隆（如 Marco 指出的那样），您可以使用自己的 Clone 函数实现此目的。

class Person
{
   public Person(Person rhs) // cctor
   {
       Age = rhs.Age;
   }

   public int Age { get; set; }

   public abstract Person Clone();
}


   public class Adult : Person
   {
       public Adult(Adult rhs) : base(rhs)
       {
           JobType = rhs.JobType;
       }

       public JobType Job { get; set; }

       public override Person Clone() { return new Adult(this); }
   }

Answer 3

您可以在基础 class 上使用简单的 class，如果您想在上层 classes 中覆盖，您可以使用虚拟的。

public abstract class Person : ICloneable {
             public virtual object Clone() {
              //all upper classes is a Person object
              person = (Person)Activator.CreateInstance(this.GetType());
                    person.job = this.job; 
                    // ect more properties Lazy or Deep clone
                    person.blah = this.blah;
                    return person;
                }
           }

public abstract class Adult : Person {
      override object Clone() {
                    Adult adult =  (Adult) base.Clone();
                    adult.job = this.job;
                }
          }

Answer 4

取 3 ...

解决方案 1：

我的首选方法是使用 ICopyTo。我认为它比其他任何东西都更可取，因为它强制具有要复制到的正确类型的对象。它还同时进行克隆和复制。更容易维护。

使用界面也有助于做正确的事。别忘了打电话 base.CopyTo ...

此外，我们可以说 CopyTo 是 Fluent interface

的一部分

public interface ICopyTo<T>
{
    T CopyTo(T target);
}

public abstract class Person : ICopyTo<Person>, ICloneable
{
    public Person CopyTo(Person person)
    {
        person.Age = Age;
        person.Country = Country;
        return person;
    }

    public abstract object Clone();

    public int Age { get; set; }
    public string Country { get; set; }
}

public abstract class Adult : Person, ICopyTo<Adult>, ICloneable
{
    public Adult CopyTo(Adult adult)
    {
        base.CopyTo(this);
        adult.Car = Car;
        return adult;
    }

    public string Car { get; set; }
}

public class Man : Adult, ICopyTo<Man>,  ICloneable
{
    public Man CopyTo(Man man = null)
    {
        if (man == null)
        {
            man = new Man();
        }
        base.CopyTo(this);
        man.Beer = Beer;

        return man;
    }


    public string Beer { get; set; }

    public override object Clone()
    {
        return CopyTo();
    }
}

public class Woman : Adult, ICopyTo<Woman>, ICloneable
{
    public Woman CopyTo(Woman woman = null)
    {
        if (woman == null)
        {
            woman = new Woman();
        }
        base.CopyTo(this);
        woman.Purse = Purse;
        return woman;
    }

    public string Purse { get; set; }

    public override object Clone()
    {
        return CopyTo();
    }
}

public class Test
{
    public static void Go()
    {
        Man man1 = new Man() {Age = 10, Beer = "Bud", Country = "Canada"};
        Man man2 = new Man();
        man1.CopyTo(man2); // Real copy

        Woman woman1 = new Woman() {Age = 32, Country = "USA", Purse = "Anything"};
        Woman woman2 = woman1.CopyTo(); // Cloning

        List<Person> adults = new List<Person>();
        adults.Add(man1);
        adults.Add(man2);
        adults.Add(woman2);

        Person person0 = adults[0].Clone() as Person;
        Person person1 = adults[1].Clone() as Person;
        Person person2 = adults[2].Clone() as Person;
    }
}

解决方案 2：（接近解决方案 1，但仅在基础 class 处使用 ICloneable）

public interface ICopyTo<T>
{
    T CopyTo(T target);
}

public abstract class Person : ICopyTo<Person>, ICloneable
{
    public virtual Person CopyTo(Person person)
    {
        if (person == null)
        {
            throw new ArgumentNullException("person can't be null");
        }

        person.Age = Age;
        person.Country = Country;
        return person;
    }

    public object Clone()
    {
        return CopyTo(null);
    }

    public int Age { get; set; }
    public string Country { get; set; }
}

public abstract class Adult : Person, ICopyTo<Adult>, ICloneable
{
    public Adult CopyTo(Adult adult)
    {
        if (adult == null)
        {
            throw new ArgumentNullException("adult can't be null");
        }

        base.CopyTo(this);
        adult.Car = Car;
        return adult;
    }

    public override Person CopyTo(Person person)
    {
        return CopyTo(person as Adult);
    }

    public string Car { get; set; }
}

public class Man : Adult, ICopyTo<Man>
{
    public Man CopyTo(Man man = null)
    {
        if (man == null)
        {
            man = new Man();
        }
        base.CopyTo(this);
        man.Beer = Beer;

        return man;
    }

    public override Person CopyTo(Person person)
    {
        return CopyTo(person as Man);
    }

    public string Beer { get; set; }
}

public class Woman : Adult, ICopyTo<Woman>
{
    public Woman CopyTo(Woman woman = null)
    {
        if (woman == null)
        {
            woman = new Woman();
        }
        base.CopyTo(this);
        woman.Purse = Purse;
        return woman;
    }

    public override Person CopyTo(Person person)
    {
        return CopyTo(person as Woman);
    }

    public string Purse { get; set; }
}

public class Test
{
    public static void Go()
    {
        Man man1 = new Man() {Age = 10, Beer = "Bud", Country = "Canada"};
        Man man2 = new Man();
        man1.CopyTo(man2); // Real copy

        Woman woman1 = new Woman() {Age = 32, Country = "USA", Purse = "Anything"};
        Woman woman2 = woman1.CopyTo(); // Cloning

        List<Person> adults = new List<Person>();
        adults.Add(man1);
        adults.Add(man2);
        adults.Add(woman2);

        Person person0 = adults[0].Clone() as Person;
        Person person1 = adults[1].Clone() as Person;
        Person person2 = adults[2].Clone() as Person;
    }
}

解决方案 3：

public static T Clone<T>(T source)
{
    if (!typeof(T).IsSerializable)
    {
        throw new ArgumentException("The type must be serializable.", "source");
    }

    // Don't serialize a null object, simply return the default for that object
    if (Object.ReferenceEquals(source, null))
    {
        return default(T);
    }

    IFormatter formatter = new BinaryFormatter();
    Stream stream = new MemoryStream();
    using (stream)
    {
        formatter.Serialize(stream, source);
        stream.Seek(0, SeekOrigin.Begin);
        return (T)formatter.Deserialize(stream);
    }
}

有没有一种方法可以通过类的层次结构来分配属性？

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有没有一种方法可以通过 类 的层次结构来分配属性？

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有没有一种方法可以通过类的层次结构来分配属性？