Contracts for C++ (design by contract) [PDF]

In this paper, we propose a Contracts facility for C++ that has been carefully considered by SG21 with a high bar set for level of consensus. The proposal includes syntax for specifying three kinds of contract assertions: precondition assertions, postcondition assertions, and assertion statements. In addition, we specify four evaluation semantics for these assertions — one non- checking semantic, ignore, and three checking semantics, observe, enforce, and quick_enforce — as well as the ability to specify a user-defined handler for contract violations. The features proposed in this paper allow C++ users to leverage contract assertions in their ecosystems in numerous ways.