Question

How do I go about if I need to initialize an object’s base with existing object? For example, in this scenario:

public class A {     public string field1;     public string field2; }  public class B : A {     public string field3;     public void Assign(A source)     {         this.base = source; // <-- will not work, what can I do here?     } } 

Assign() method can, obviously assign values to the base class field-by-field, but isn’t there a better solution? Since class B inherits from A, there must be a way to just assign A to the B.base

In C++ this would be a trivial thing to do, but I can’t seem to grasp how to do this in .NET

Answer 1

Unfortunately base is readonly.

[Edit]
Well perhaps not so unfortunate. The relationship between a base class and a child class is IS-A not HAS-A. By allowing a child class to change the instance of the base class you are allowing the child class to change its own reference since it IS-A base class. If you truly need this functionality then I would suggest you change your inheritance model to reflect what you truly want to do.

Something like this:

public class A {     public string field1;     public string field2; }  public class B {     public string field3;     public A a;      public void Assign(A source)     {         this.a = source;     } } 

seems more appropriate and has clearer meaning and functionality.