Comment by bostonsre

It's been a while since I've read it, but I think to handle boolean flag type logic well he suggests to rely on object subclassing instead. So, for an example that uses a dry run flag for scary operations, you can have your normal object (a) and all of its methods that actually perform those scary operations. Then you can subclass that object (a) to create a dry run subclass (b). That object b, can override only the methods that perform the scary operations that you want to dry run while at the same time using all of its non scary methods. That would let you avoid having if dry_run == true; then dry_run_method() else scary_method() scattered in lots of different methods.