从虚拟方法访问派生类

Question

Though many questions on this topic exist, I am unable to find (yet) a satisfying solution:

Is it possible (and if yes, how?) to access a derived class from the base virtual method?

---

Let's imagine I have the following classes:

public class parent_class
{
    public virtual string common_method () {
        dynamic child =  /* something to access the derived class */ ;

        if (child == null)
            return typeof(parent_class).FullName;
        else
            return child.GetType().FullName;
    }   
}

public class child_class1 : parent_class {}
public class child_class2 : parent_class {}
public class child_class3 : parent_class {}

Is it possible to execute the following code (and getting the correct result)?

parent_class p = new parent_class();
child_class1 c1 = new child_class1();
child_class2 c2 = new child_class2();
child_class3 c3 = new child_class3();

System.Console.WriteLine(p.common_method()); // result:  'parent_class'
System.Console.WriteLine(c1.common_method()); // result:  'child_class1'
System.Console.WriteLine(c2.common_method()); // result:  'child_class2'
System.Console.WriteLine(c3.common_method()); // result:  'child_class3'

---

EDIT: After reading the comments and replies I have to add the following points:

• I have about 300 different "child classes", so overriding is not an option
  
• I do not want to print the derived class' name - It was just an example
  
• @Siamak Ferdos: I tried the this -keyword, but it somehow did not work as I intended.

Answer 1

Yes you can do it by 'this' keyword simply:

public class parent_class
    {
        public virtual string common_method()
        {
            //dynamic child =  /* something to access the derived class */ ;

            if (this.GetType() == typeof(parent_class))
                return typeof(parent_class).FullName;
            else
                return this.GetType().FullName;
        }
    }

    public class child_class1 : parent_class { }
    public class child_class2 : parent_class { }
    public class child_class3 : parent_class { }

Answer 2

If I understand your question correctly, you want to print the classes full name via a common base class method. At runtime, the actual instantiated type name is what GetType().FullName will produce, not the type of the base class.

This can be tested with a simple example:

void Main()
{
    var parent = new Parent();
    var child = new Child();

    Console.WriteLine(parent.GetName());
    Console.WriteLine(child.GetName());
}

public class Parent
{
    public string GetName()
    {
        return this.GetType().FullName; 
    }
}

public class Child : Parent
{
}

Yields:

UserQuery+Parent
UserQuery+Child

Where UserQuery is the defined namespace.

There is no need for the method to be virtual or overriden in the derived class for this to work.