c# - 有没有一种方法可以通过类的层次结构来分配属性？

Question

请看下面的类层次结构:

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

每个派生类都有特定的属性:例如，成人可能有工作，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。一个男孩也有学校的名字，但他没有喜欢的娃娃。

我想实现一个克隆 Boy 的方法(返回一个具有完全相同属性的 Boy 对象)。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，所以我需要对克隆的对象进行一些控制.

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

Answer 1

取 3 ...

解决方案一:

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。更易于维护。

使用界面也有助于做正确的事。不要忘记调用 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，但仅在基类使用 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);
    }
}