var-args and macros? Sure!

I didn’t realize until recently that this works:

#define WED_ThrowPrintf(fmt, …) \
throw wed_error_exception(__FILE__, __LINE__, fmt, __VA_ARGS__)
The reason I like var-args and macros together: they make thorough error reporting relatively easy in C++ without a lot of code.

if (err != noErr) WED_ThrowPrintf(”Unable to open document %s (OS Error %d: %s)”, file_name.c_str(), err, OSTranslate(err));

C++ makes almost anything possible, but does it make it easy? I’m a lazy human programmer; the easier a subsystem is to use, the more I’ll use it. So it makes sense to make good practices easier. The easier it is to encode a lot of context information into an error report, the more likely I am to do it, and the more likely a field-report of an error will contain useful diagnostic information.