这是复制课程的好方法吗？

Question

我是一个完整的菜鸟,所以如果我不在乎这个问题,请告诉我,如果需要,请告诉我.无论如何......我一直在学习值类型和引用类型,我想知道是否定义一个额外的构造函数(如稍后调用它)是一种创建类副本的有效方法.我尝试用一​​个简单的类测试它,它似乎工作.

public ClassClass(ClassClass exampleClass)
    {
        var1 = exampleClass.var1;
        var2 = exampleClass.var2;
        // ...
    }

...

Answer 1

有两种复制对象.

1. 参考副本
2. 价值复制

通过引用复制对象,您只需使用'='运算符即可.

例如:

var o1 = new ClassClass();
var o2 = o1;

按值复制对象有几种方法,例如:

由构造函数复制(如您所写)

    public class Student
    {
        public string FirstName { get; set; }
        public string LastName { get; set; }

        public Student(Student std)
        {
            FirstName = std.FirstName;
            LastName = std.LastName;
        }
    }

使一个辅助类传递s1作为输入并返回s2作为结果

    static void Main(string[] args)
    {
        var s1 = new Student();
        var s2 = ClassHelper.CopyObject(s1);

    }

    public static class ClassHelper
    {
        public static Student CopyObject(Student std)
        {
            var newStudent = new Student()
            {
                FirstName = std.FirstName,
                LastName = std.LastName
            };
            return newStudent;
        }
    }

通用复制对象(使用Refelection)

private static void CopyClass<T>(T copyFrom, T copyTo, bool copyChildren)
{
    if (copyFrom == null || copyTo == null)
        throw new Exception("Must not specify null parameters");

    var properties = copyFrom.GetType().GetProperties();

    foreach (var p in properties.Where(prop => prop.CanRead && prop.CanWrite))
    {
        if (p.PropertyType.IsClass && p.PropertyType != typeof(string))
        {
            if (!copyChildren) continue;

            var destinationClass = Activator.CreateInstance(p.PropertyType);
            object copyValue = p.GetValue(copyFrom);

            CopyClass(copyValue, destinationClass, copyChildren);

            p.SetValue(copyTo, destinationClass);                  
        }
        else
        {
            object copyValue = p.GetValue(copyFrom);
            p.SetValue(copyTo, copyValue);
        }
    }
}

为这个类写一个扩展方法,我建议这样做.

public static class ExtensionClass
{
    public static Student CopyAsNewObject(this Student std)
    {
        var newStudent = new Student()
        {
            FirstName = std.FirstName,
            LastName = std.LastName
        };
        return newStudent;
    }
}

    static void Main(string[] args)
    {
        var s1 = new Student();
        var s2 = s1.CopyAsNewObject();
    }