A problem that I see with these approaches (e.g. 1..5) is that the possible values are often not set in stone. This means that by using range constraints or sim

A problem that I see with these approaches (e.g. 1..5) is that the possible values are often not set in stone. This means that by using range constraints or similar, there is often an overspecification that can hurt down the road. Furthermore, the possible values differ from location to location as the values travel through the program. In that sense, the possible values are often underspecified / underconstrained, even though the specifications are already not simple. This is why I prefer to go with rather little constraints - in a compiled language, you have to specify the physical layout (8/16/32/64 bits?), and I try to specify not more than that in most cases. Then, so much safety can be achieved by placing asserts in strategic locations.