CppCon 2024

Design by Contract is a very effective approach for writing safer, more correct programs. It has been successfully implemented in programming languages like Eiffel and Ada. Attempts to add a Contracts facility to C++ have a long and storied history spanning two decades. Since the last attempt to standardise Contracts (for the C++20 Standard) has failed, SG21 — the Contracts Study Group on the C++ Standard Committee – has been working on a new design, the so-called Contracts MVP, which is now essentially feature-complete and on track to make it into the upcoming C++26 Standard.

In this talk, we present the current design of the Contracts MVP targeting C++26. We discuss preconditions, postconditions, assertions, contract-violation handling and much more. We consider how the Contracts MVP provides a superior replacement for custom assertion macros and, when used correctly, can significantly improve the safety and correctness of your code.