> It is often tempting to shortcut this by passing in some kind of option flag to existing code, rather than enabling a full parallel implementation. I've fall

> It is often tempting to shortcut this by passing in some kind of option flag to existing code, rather than enabling a full parallel implementation. I've fallen into this trap, with a horrible mess of conditions. But you still need some kind of flag, right? To switch which implementation to run. He's talking about modules, not entirely separate standalone programs, so I guess he means the flag is outside the implementations chosen between (and never passed into any of them). EDIT He's using console/environment flags, so it just needs a little code to read flags, and switch implementations. > The difference between changing a console variable to get a different behavior versus running an old exe, let alone reverting code changes and rebuilding, is significant.