Question

You can check if an object is null but can you check if an object is valid?

Assert.IsValid(object_name);

For example, the object has been deleted by the garbage collector or someone has done dispose on it. But the pointer is still pointing to that object.

Answer 1

If the object has been freed by the garbage collector, you won’t have a reference to it, by definition.

If it’s been disposed and that’s important to the object’s validity, the type ought to provide a way of determining that. (In some cases Dispose can just mean “reset”, for example.)

It’s rarely appropriate to even allow the possibility of having a reference to a disposed object though – if you use:

using (Foo foo = new Foo())
{
    ...
}

then the object will be disposed at the same time that foo goes out of scope, so this isn’t an issue.