Re: [libvirt] [PATCH] libvirt, logging: cleanup VIR_DEBUG0() VIR_INFO0() VIR_WARN0() VIR_ERROR0()

On 05/10/2011 08:52 AM, Eric Blake wrote: But, we CAN do: #ifdef __GNUC__ # define high_level(fmt, ...) low_level(fmt, ##__VA_ARGS__) #else # define PP_NARG(...) \ PP_NARG_(__VA_ARGS__,PP_RSEQ_N()) # define PP_NARG_(...) \ PP_ARG_N(__VA_ARGS__) # define PP_ARG_N( \ _1, _2, _3, _4, _5, _6, _7, _8, _9,_10, \ _11,_12,_13,_14,_15,_16,_17,_18,_19,_20, \ _21,_22,_23,_24,_25,_26,_27,_28,_29,_30, \ _31,_32,_33,_34,_35,_36,_37,_38,_39,_40, \ _41,_42,_43,_44,_45,_46,_47,_48,_49,_50, \ _51,_52,_53,_54,_55,_56,_57,_58,_59,_60, \ _61,_62,_63,N,...) N # define PP_RSEQ_N() \ 63,62,61,60, \ 59,58,57,56,55,54,53,52,51,50, \ 49,48,47,46,45,44,43,42,41,40, \ 39,38,37,36,35,34,33,32,31,30, \ 29,28,27,26,25,24,23,22,21,20, \ 19,18,17,16,15,14,13,12,11,10, \ 9,8,7,6,5,4,3,2,1,0 # define VIR_DEBUG(...) VIR_DEBUG ## PP_NARG(__VA_ARGS__) (__VA_ARGS__) # define VIR_DEBUG1(xxx) xxx # define VIR_DEBUG2(xxx, xxx) xxx ... # define VIR_DEBUG63(xxx, ..., xxx) xxx #endif suitably expanded (and we can also place a cap on the maximum number of arguments we ever expect to see in VIR_DEBUG, rather than going all the way to the C99 limit of 63). Thanks to: https://groups.google.com/group/comp.std.c/browse_thread/thread/77ee8c8f9... for the idea. Yeah, it's gross, but we limit the grossness to one header, and the rest of the code is more maintainable as a result. -- Eric Blake eblake(a)redhat.com +1-801-349-2682 Libvirt virtualization library http://libvirt.org