Over at CXF, we've got a fairly large set of prescriptive rules via PMD and checkstyle. There are some advantages to this. As the number of committers grows, you never have to worry about having to make sense of, for maintenance purposes, some really creative choice of naming, or formatting. We've been operating this way for a long time.
It does mean that each of us has accepted some style bits that we don't much like. Are the advantages worth the annoyance? I can't prove it. It may be that the problem domain at CXF is different in a significant way from Mahout. Because the rules are prescriptive (maven and eclipse check them), anyone working on a patch is highly motivated to use the relevant format from the start. Pretty clearly, some of us here at Mahout are not attracted to this mode of operation. If we're just going to treat CS as a tool for checking for bears, and not set the build to enforce, then I think we need a minimal set of rules that don't treat on any toes, and those with time and inclination can make fixes in the least intrusive way they can think of. The sooner we make the fixes, the smaller the number of long-running patches that can get caught across a transition.
