Au Idioms

This section covers common idioms and usage patterns you’ll encounter in using Au. These concepts can make you more effective with this library, but may not help with other units libraries.

• Abbreviated quantity construction. Most C++ units libraries provide user-defined literals (UDLs) to make quantities in a concise, readable way — think 3.5_m instead of meters(3.5). We’ll explain why Au initially rejected this approach, what we have provided instead, and finally, the innovative and surprising solution that supercharged UDLs and fixed their most glaring problems for quantities.

• Namespaces and includes. Which headers to include, and how to bring Au’s names into scope — including why the answer differs between implementation files and headers.

• Unit slots. Many Au APIs have parameters that accept an explicitly named unit. We call these paremeters “unit slots”. This page will explain what kinds of things can go in that slot, and which ones to prefer in different situations.