Managing Quantities and Units of Measurement in Code Bases

Quantities in engineering and the physical sciences are expressed as units of measurement (UoM). If a software system fails to maintain the algebraic attributes of a system’s UoM information correctly when evaluating expressions then disastrous problems can arise. However, it is perhaps the more mundane unit mismatches and lack of interoperability that over time incurs a greater cost. Global and existential challenges, from infectious diseases to environmental breakdown, require high-quality data. Ensuring software systems support quantities explicitly is becoming less of a luxury and more of a necessity. While there are technical solutions that allow units of measurement to be specified at both the model and code level, a detailed assessment of their strengths and weaknesses has only recently been undertaken. This chapter provides both a formal introduction to managing quantities and a practical comparison of existing techniques so that software users can judge the robustness of their systems with regards to units of measurement.