Question

    class MainClass { 
      private int someMethod() { 
    IList <SubClass> obj = db.Query <SubClass> (delegate(SubClass obj) { 
      return obj.Points == 100; 
    });
}
    } 

    class SubClass : MainClass { 
        public int someField; 
    } 

    SubClass obj = new SubClass(); 
    obj.someMethod();

SubClasses可能有所不同，我需要获取此实例才能对db4o进行查询。

Answer 1

从基类中评估子类类型以进行一些处理，通常是一个错误的决定，考虑将一个组合的方法添加到基类，然后利用专门的处理到它的子类：

class MainClass {
    public string ComposedMethod(){
        //Base class processing...
        var retVal = someMethod();
        //Even more Base class processing...
        return retVal; 
    } 
    public virtual string someMethod(){ 
    } 
} 

class SubClass : MainClass { 
    public override string someMethod(){
        return this.GetType().ToString(); //Or whatever you need to do
    } 
}

用法：

SubClass obj = new SubClass(); 
obj.ComposedMethod();

Answer 2

class MainClass
{
    public string someMethod()
    {
        Type type = this.GetType(); //SubClass
        return "";
    }
}

class SubClass : MainClass
{
    public int someField;
}

它是一个黑客，但不推荐，因为它不符合多态的目的。

C＃获取subClass的类型并创建它的对象

2 个答案: