c# – 根据值确定要创建的派生类？

我想知道这是否可能.我有许多类都是从相同的基类(BaseClass)派生的.当我创建一个实例时,我需要根据配置值决定我需要创建哪个派生类.目前我正在做下面的事情,但我希望有一个更简洁的方法来实现这一点,如果我需要添加一个新的派生类,需要更少的维护.

BaseClass myclass;
switch (Config.ClassToUse)
{
   case 1: 
        myclass= new DerivedClass1(Config); 
        break;
   case 2: 
        myclass= new DerivedClass2(Config);
        break;
   case 3: 
        myclass = new DerivedClass3(Config);
        break;
}
myclass.DoWork();

DoWork方法中的代码因类的每个不同实例而异.

希望有道理.

解决方法:

这是Config,知道要创建哪个类,这就是为什么让我们Config完成它的工作.我们应该摆脱神奇的数字(2代表什么？)并返回Type,而不是int.

快速补丁是

public class Config { 
  ...
  // Get rid of this, move logic into TypeToUse
  public int ClassToUse {get { ... }}

  public Type TypeToUse {
    get {
      string name = $"DerivedClass{ClassToUse}";

      // Here we scan all types in order to find out the best one. Class must be
      //   1. Derived from BaseClass
      //   2. Not Abstract (we want to create an instance)
      // Among these classes we find the required by its name DerivedClass[1..3]
      // (as a patch). You should implement a more elaborated filter
      // If we have several candidates we'll take the 1st one
      return AppDomain
        .CurrentDomain
        .GetAssemblies()         // scan all assemblies  
        .SelectMany(asm => asm
          .GetTypes()            // and all types 
          .Where(tp => typeof(BaseClass).IsAssignableFrom(tp))) // ... for derived classes
       .Where(tp => !tp.IsAbstract)       //TODO: Add more filters if required
       .Where(tp => tp.Name.Equals(name)) //TODO: put relevant filter here 
       .FirstOrDefault();            
    }
  } 

  public BaseClass CreateInstance() {
    Type tp = TypeToUse;

    if (tp == null)
      return null; // Or throw exception

    return Activator.CreateInstance(tp, this) as BaseType;
  } 
} 

然后你可以把

BaseClass myclass = Config.CreateInstance();

myclass.DoWork();

标签：c,inheritance,derived-class
来源： https://codeday.me/bug/20190701/1346538.html