How to aliase a function with variable number of arguments?

Question

I have a method in a class with this signature:

void addMessage_( std::string appender, LogLevel level /*= LOGLEVEL_INFO*/, char* msg, ... );

I want to create 'alias' of this method in this way:

void debugMsg( std::string appender, char* msg, ... ){
 addMessage(appender, LOGLEVEL_DEBUG, msg, ...);
}

My question is: do I need to expand the args to call the addMessage method? I don't want to replicate the code I each utility method, but I don't want to waste performance. What is the best solution?

Solved: I let my solution as a documentation:

void DEBUG_MSG(std::string appender, char* msg, ...){
 va_list argptr;
 va_start(argptr,msg);
 addMessage_(appender, LOGLEVEL_DEBUG, msg, argptr);
 va_end(argptr);
}

And the addMessage_ method:

 void CGlobalLog::addMessage_( std::string appender, LogLevel level, char* msg, va_list args ){
 int len;
 char *buffer;
 len = _vscprintf( msg, args ) // _vscprintf doesn't count
 + 1; // terminating '0円'
 buffer = (char*)malloc( len * sizeof(char) );
 vsprintf( buffer, msg, args ); // C4996
 // Note: vsprintf is deprecated; consider using vsprintf_s instead
 addMessage(buffer,appender,level);
 free( buffer );
}

Thanks!

Answer 1

It's not possible that way (without macros), you must change your original function to take a va_list.

It is fully explained here: Passing variable number of arguments around

Answer 2

Macro can solve that in just one line:

#define debugMsg(appender,msg,...) addMessage(appender,LOGLEVEL_DEBUG, msg, __VA_ARGS__)

Or, you've to make use of va_list, va_start and va_end as explained here.