The technique used here is called "X Macro". There are article on wikipedia and wikibooks. https://en.wikipedia.org/wiki/X_Macro https://en.wikipedia.org/wiki/

The technique used here is called "X Macro". There are article on wikipedia and wikibooks. https://en.wikipedia.org/wiki/X_Macro https://en.wikipedia.org/wiki/X_Macro https://en.wikibooks.org/wiki/C_Programming/Preprocessor#X-Macros https://en.wikibooks.org/wiki/C_Programming/Preprocessor#X-M... It's very useful in some situations. It offers, in a way, a mean to do a sort of compile-time introspection on some class/enum.