Using macros with a logger

[Mybowlcut]

Hey.

I want to do this:

void f()
{
    LOG("Called f().");
}

But I only want the LOG macro to work if USE_LOG is defined... in other words, if USE_LOG isn't defined, the LOG macro won't do anything. I'm trying to write the macro for this but I can't get it right:

#ifndef LOG(string)
#define LOG(string)
#ifdef USE_LOG
Logger::Get().Log(string)
#endif
#endif

This gives me a warning:

warning C4067: unexpected tokens following preprocessor directive - expected a newline	c:\...\logger.h

Also I'm just not sure if it will do what I think it will do... if USE_LOG isn't defined and the call "disappears" everywhere it is used in code, will it leave behind semicolons everywhere? If so, is this a bad thing? Will the compiler interpret these as statements and spend time processing them?

Cheers.