In an embodiment, a system may include a processor having memory storing processor-executable instructions for a programming environment. The processor may perform the following instructions. A first, second, and third class may be defined. The second class may be defined as being compatible with the first class. The third class may be defined as being incompatible with the first class. A fourth class may be defined as a subclass of both the first class and the second class. A fifth class may be prevented from being a subclass of both the first class and the third class.