Question

What is the highest class in the hierarchy I can use to pass HttpSessionState as a parameter and add values to it?

For instance to a method like

public void MyMethod(IDictionary<string, object> input)
{
    input.Add("something", something);
}

I see that implements ICollection and IEnumerable, but that only allows me to read values, not add them.

Answer 1

ICollection is the best you can do.

You could wrap it in something that implements IDictionary<string,object> if you wanted it to be more convenient.