Question

I tried to insert an object into a generic BindingList.
But if I try to add a specific object the compiler says:
“Argument type … is not assignable to parameter type”

private void JoinLeaveItem<T>(BindingList<T> collection)
    {

        if (collection.GetType().GetGenericArguments()[0] == typeof(UserInformation))
        {
            var tmp = new UserInformation();
            collection.Add(tmp);
        }
    }

Please help me

Answer 1

You cannot have objects of two different types that does not have a common anscestor in a strongly typed list. That is: In your case you will need to different collections unless your two (or more) classes have a common base class.

Try creating overloads instead, like this

private void JoinLeaveItem(BindingList<UserInformation> collection)
{
    collection.Add(new UserInformation());
}

private void JoinLeaveItem(BindingList<GroupInformation> collection)
{
    collection.Add(new GroupInformation());
}

Use it like this

JoinLeaveItem(userInformationCollection)
JoinLeaveItem(groupInformationCollection)

Note: I’ve inlined the tmp variable.