c# - 在构造函数中克隆类

Question

我需要类似的东西

public class  object_t 
{

    public object_t ( string config, object_t default_obj )
    {
         if( /*failed to initialize from config*/ )
         { 
            this = default_obj; // need to copy default object into self
         }
    }
 }

我知道这是不正确的。如何实现这个构造函数？

Answer 1

最常见的可能是使用静态工厂方法:

public class object_t 
{    
    public static object_t CreateObjectT(string config, object_t default_obj)
    {
         object_t theconfiguredobject = new object_t();

         //try to configure it

         if( /*failed to initialize from config*/ )
         { 
             return default_obj.Clone();
         }
         else
         {
             return theconfiguredobject;
         }
    }
}

---

执行上述操作的更好方法是创建一个复制构造函数:

public object_t (object_t obj)
    : this()
{
    this.prop1 = obj.prop1;
    this.prop2 = obj.prop2;
    //...
}

以及尝试从配置字符串创建对象的方法:

private static bool TryCreateObjectT(string config, out object_t o)
{
    //try to configure the object o
    //if it succeeds, return true; else return false
}

然后让你的工厂方法首先调用 TryCreateObjectT，如果失败，复制构造函数:

public static object_t CreateObjectT(string config, object_t default_obj)
{
     object_t o;
     return TryCreateObjectT(config, out o) ? o : new object_t(default_obj);
}