C#: Create strong reference between objects, without one referencing the other

Question

Suppose I have 2 classes, Foo and Bar. Foo does not have (and cannot have) a relation to Bar.

However, I want a bar instance to stay alive, as long as it\'s foo instance

Answer 1

Have a look at the ConditionalWeakTable Class.

Enables compilers to dynamically attach object fields to managed objects.

It's essentially a dictionary where both the key and the value are a WeakReference, and the value is kept alive as long as the key is alive.

For example, you can define a

ConditionalWeakTable table

and add a Foo/Bar pair. The Bar instance is kept alive as long as a reference to the Foo instance exists. You can find the Bar instance for the Foo instance by looking at the table.