Don't abuse new to do a reinterpret_cast

Using new to do a reinterpret_cast is rather confusing.
Also protect the list model case against self-assignment
which could lead to memory corruption.

Change-Id: I10b81644d0004d4a50a5a74e5b8c58e27cbe6934
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>