variadic-macros

I run cl /P test.cpp, the file and result is as following. test.cpp #define FiltedLog( ...) \ if (logDetail) \ MP_LOG(LOG_INFO, __VA_ARGS__); #define MP_LOG(level,fmt,...) \ BOOAT::LOG("MP", level, fmt, ##__VA_ARGS__) #define LOG(tag,level,fmt,...) \ Log::log(tag, level, "%s: " fmt, __PRETTY_FUNCTION__, ##__VA_ARGS__) int main () { FiltedLog ( "abc", 1, 2); } Cl /P test.cpp : #line 1 "test.cpp" int main () { if (logDetail) BOOAT::Log::log("MP", LOG_INFO, "%s: " "abc", 1, 2, __PRETTY_FUNCTION__ );; } I wonder why the __PRETTY_FUNCTION__ are put as the last arguments in the result. I assume the

/* Debugging */ #ifdef DEBUG_THRU_UART0 # define DEBUG(...) printString (__VA_ARGS__) #else void dummyFunc(void); # define DEBUG(...) dummyFunc() #endif I've seen this notation in different headers of C programming, I basically understood it's passing arguments, but I didn't understand what this "three dots notation" is called? Can someone explain it with example or provide links also about VA Args? The dots are called, together with the __VA_ARGS__ , variadic macros When the macro is invoked, all the tokens in its argument list [...], including any commas, become the variable argument . This

A typical LOG() macro-based logging solution may look something like this: #define LOG(msg) \ std::cout << __FILE__ << "(" << __LINE__ << "): " << msg << std::endl This allows programmers to create data rich messages using convenient and type-safe streaming operators: string file = "blah.txt"; int error = 123; ... LOG("Read failed: " << file << " (" << error << ")"); // Outputs: // test.cpp(5): Read failed: blah.txt (123) The problem is that this causes the compiler to inline multiple ostream::operator<< calls. This increases the generated code and therefore function size, which I suspect may

I am trying to write a macro dbgassert similar to the standard assert . In addition to what assert does, I want to dbgassert print an arbitrary number of additional parameters (containing debugging information). What I have so far is listed below, which is adapted from this SO answer . But I am having issue in my code with either variadic templates or macros. If I use at least one additional argument (the OK line), then dbgassert works as expected. But if I give no additional argument, then compilation fails (the problem line). I have some experience with variadic template programming (like

I would like to have a group of variable number of arguments passed into a macro. I have following macros which is incorrect: #define M_NARGS(...) M_NARGS_(__VA_ARGS__, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0) #define M_NARGS_(_10, _9, _8, _7, _6, _5, _4, _3, _2, _1, N, ...) N #define M_CONC(A, B) M_CONC_(A, B) #define M_CONC_(A, B) A##B #define M_ID(...) __VA_ARGS__ #define M_LEFT(L, R) L #define M_RIGHT(L, R) R #define M_FOR_EACH(ACTN, ...) M_CONC(M_FOR_EACH_, M_NARGS(__VA_ARGS__)) (ACTN, __VA_ARGS__) #define M_FOR_EACH_0(ACTN, E) E #define M_FOR_EACH_1(ACTN, E) ACTN(E) #define M_FOR_EACH_2(ACTN, E