Self-test Code Block Macro

Self-test Code Block Macro

An alternative formulation of a macro for installing self-testing code using a block-style, rather than a function-like macro, is as follows:

    SELFTEST {
        // block of debug or self-test statements
    }

The definition of the SELFTEST macro looks like:

    #if YDEBUG
    #define SELFTEST // nothing (enables!)
    #else
    #define SELFTEST if(1) {} else // disabled
    #endif

This method relies on the C++ optimizer to fix the non-debug version, by noticing that “if(1)” invalidates the else clause, so as to remove the block of unreachable self-testing code that's not ever executed.

Note also that SELFTEST is not function-like, so we don't have the “forgotten semicolon” risk when removing SELFTEST as “nothing”. In fact, the nothing version is actually when SELFTEST code is enabled, which is the opposite situation of that earlier problem. Furthermore, we cannot use the “do-while(0)” trick in this different syntax formulation.