Force the Qt MOC to expand some custom macros?

Question

Is it possible to force the Qt MOC to expand some of my custom preprocessor defines to achieve some kind of 2-pass preprocessing? E.g.:

// MOC macro
@MOC #define add(a, b) (a + b) // Should be expanded by MOC (1st run)

// "Normal" macro
#define sub(a, b) (a - b) // Should be expanded by preprocessor (2nd run)

Do you mean, have something defined only when moc is run? You can wrap it in `#ifdef Q_MOC_RUN`. Not sure what you mean by "2-pass preprocessing". — peppe, Apr 22 '18 at 12:19

score 1 · Accepted Answer · answered Apr 22 '18 at 14:49

If your goal is to enable or disable some macros only during the Moc pass, you can test the Q_MOC_RUN define as hinted by peppe.

#ifdef Q_MOC_RUN
#define MyMacro valueDuringMoc
#else
#define MyMacro defaultValue
#endif

If you want to build your own pre-processor rules relying on the same mechanism as MOC, i.e. generating additional C++ code in a .h files included in final build, then you should have a look at that other question.

Thats it (in the link)! Thanks! – FlKo Apr 22 '18 at 17:13 — FlKo, Apr 22 '18 at 17:13

Force the Qt MOC to expand some custom macros?

1 Answers1