How to copy generically superclass instances to subclass instances?
- by gerry
Hi @all,
I have a class hierarchy / inheritance like this:
public class A {
private String name;
// with getters & setters
public void doAWithName(){
...
}
}
public class B extends A {
public void doBWithName(){
// a differnt implementation to what I do in class A
}
}
public class C extends B {
public void doCWithName(){
// a differnt implementation to what I do in class A and B
}
}
So at one time there is a instance of class A with the initialized field "name". Later I want this instance of A get wrapped into instance of B or C. So the superclasses should be get wrapped with a subclass!
How can I make this most efficent with respect to DRY?
I've thought about a constructor that does some copying with the getters/setters. But in this case I have to repeat myself - and this doesn't respect anymore to my initial requirement of DRY!
So, how can I warp A to B by just initializing B's new fields (with default values) and delegating the rest to a method in A (which knows more than B about which fields of A should be accessed...).
In the same way:
If A should be wrapped into C only a method in c should init C's 'new' fields, delegate to B's wrap method (which therefore inits B's 'new' fields in C) and at last B delegates to A which copies it's fields to the fields of C).
So in the end I have a new instance of C which has the values of A wrapped (and some default init values to the fields which the inheritance hierarchy has added).
