Object Design: Roles, Responsibilities, and Collaborations

Chapter 4. Responsibilities

Christopher Alexander states, “Form is part of the world over which we have control, and which we decide to shape while leaving the rest of the world as it is.” The measure of a design’s goodness is how well the form fits into its context. When we shape an object’s responsibilities, we are inventing a form that should fit smoothly into its environment. We have the luxury of shaping both form and context when we distribute responsibilities among collaborators.

The rightness of a form, according to Alexander, depends on how effortlessly it contacts with its environment. To make informed decisions about an object’s responsibilities, we should divide form and context across several dimensions and consider several aspects ...