问题描述

我的问题显示在这段代码中

My question is shown in this code

我有这样的课

public class MainCS
{
  public int A;
  public int B;
  public int C;
  public int D; 
}

public class Sub1
{
  public int A;
  public int B;
  public int C;
}


public void MethodA(Sub1 model)
{
  MainCS mdata = new MainCS() { A = model.A, B = model.B, C = model.C };   

  // is there a way to directly cast class Sub1 into MainCS like that    
  mdata = (MainCS) model;    
}

推荐答案

他想说的是:

如果你有两个类共享大部分相同的属性，你可以将一个对象从类 a 转换为类 b 并自动让系统通过以下方式理解分配共享属性名称?"

"If you have two classes which share most of the same properties you can cast an object from class a to class b and automatically make the system understand the assignment via the shared property names?"

选项1:使用反射

缺点:它会比你想象的更慢.

Disadvantage : It's gonna slow you down more than you think.

选项 2:让一个类从另一个类派生，第一个类具有公共属性，其他类是该类的扩展.

Option 2: Make one class derive from another, the first one with common properties and other an extension of that.

缺点:耦合！如果您在应用程序中为两层执行此操作，那么这两层将被耦合！

Disadvantage: Coupled! if your're doing that for two layers in your application then the two layers will be coupled!

假设:

class customer
{
    public string firstname { get; set; }
    public string lastname { get; set; }
    public int age { get; set; }
}
class employee
{
    public string firstname { get; set; }
    public int age { get; set; } 
}

现在这里是对象类型的扩展:

Now here is an extension for Object type:

public static T Cast<T>(this Object myobj)
{
    Type objectType = myobj.GetType();
    Type target = typeof(T);
    var x = Activator.CreateInstance(target, false);
    var z = from source in objectType.GetMembers().ToList()
        where source.MemberType == MemberTypes.Property select source ;
    var d = from source in target.GetMembers().ToList()
        where source.MemberType == MemberTypes.Property select source;
    List<MemberInfo> members = d.Where(memberInfo => d.Select(c => c.Name)
       .ToList().Contains(memberInfo.Name)).ToList();
    PropertyInfo propertyInfo;
    object value;
    foreach (var memberInfo in members)
    {
        propertyInfo = typeof(T).GetProperty(memberInfo.Name);
        value = myobj.GetType().GetProperty(memberInfo.Name).GetValue(myobj,null);

        propertyInfo.SetValue(x,value,null);
    }   
    return (T)x;
}  

现在你可以这样使用它:

Now you use it like this:

static void Main(string[] args)
{
    var cus = new customer();
    cus.firstname = "John";
    cus.age = 3;
    employee emp =  cus.Cast<employee>();
}

方法转换检查两个对象之间的公共属性并自动进行分配.

Method cast checks common properties between two objects and does the assignment automatically.

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