How to Use Objects: Code and Concepts

Chapter 6. Fine Print in Contracts

Contracts form a solid framework for arguing about the correctness of ⁴ code: Class invariants capture the consistency of the objects’ internal structures, while the pre- and post-conditions of methods describe the objects’ behavior to clients without requiring knowledge of the objects’ internals. Within methods, the workings of the code can be traced in detail, down to ^4.2.3 formalizing the effects of individual statements. ^4.7

The presentation so far has established the terminology and common reasoning patterns. ...