CppCon 2023

API or math mistakes with units can cause problems ranging from a digital audio processing outputting silence to crashing your Mars rover—we’ll discuss real-life examples of both!

The combination of user-defined types, conversion operators/constructors, and operator overloading in C++ give us the tools to use strong-types and avoid unit mistakes; std::chrono is a great example of this that everyone should be using. Unfortunately, when dealing with units beyond time many developers still use primitive types encoding units in variable names or comments because the standard does not offer any tools for user-defined units.

In this talk we will look at the mp-units library which has been proposed for standardization in P1935 (A C++ Approach to Physical Units). We will look at the implementation of various units used in digital audio / DSP that go beyond “physical” units and what the experience is like to develop your own units with this library/proposal.