Daily bit(e) of C++ | Inline variables
Daily bit(e) of C++ #376, C++17 inline variables.
C++17 introduced inline variables.
Inline variables can appear in headers as they are permitted multiple definitions (as long as there is only one per unit and all definitions are the same).
One of the notable use cases of inline variables is for customization function objects (Niebloids) since non-function symbols inhibit ADL lookup.
