Question

In my application I have a class which has properties of user-defined types like this:

class MyType
{
    public A MyProperty
    {
        get;
        set;
    }
}
class A
{
    .....some methods and proeprties
}

for some operations that I need to perform from my main program, I have created a List of A and add in to it MyProperty whenever creating object of MyType

List<A> myList = new List<A>();

MyType m1 = new MyType();
myList.Add(m1.MyProperty);

MyType m2 = new MyType();
myList.Add(m2.MyProperty);

......more instances

and pass it to my main program and there I perform different operation on these properties which reflects in there instances also. Is there any way by which I could get the object instance for any particular MyProperty from that property in the list.

Answer 1

I suspect you mean you’re creating a List<A> and you want to be able to find out from an instance of A which instance of MyType “owns” it. There’s no way of doing that without putting the information in A (or having a comprehensive list of instances of MyType and checking them). After all, two instances of MyType could have the same A:

MyType first = new MyType();
MyType second = new MyType();
A a = new A();
first.MyProperty = a;
second.MyProperty = a;

Which MyType is a logically associated with? Both or neither, really…

The cleanest approach is to make A know about which MyType it’s associated with explicitly – then you can decide what should happen if you try to have one instance of A associated with two instances of MyType (should it throw an exception? Keep both as a list? Keep the newer?) You probably want to make the MyType.MyProperty update the value that’s passed in, to keep the association in sync.