The design style in this book largely follows the principle of “responsibility-driven design,” put forward in Wirfs-Brock et al. 1990 and updated in Wirfs-Brock 2003. It also draws heavily (especially in Part III) on the ideas of “design by contract” described in Meyer 1988. It is consistent with the general background of other widely held best practices of object-oriented design, which are described in such books as Larman 1998.

