Conditionally compiling C++ macros

[yasmin]

I am trying to conditionally compile macros in my c++ program.
I want to simply be able to use the macro name without enclosing it in #ifdef-#endif each time. How can I enclose the macro definition itself in a #ifdef-#endif?

Here's my example:

#define FAULT
    { \ 
          if (test.exists()) { \
              return error( "Aborting" ); \
          } \
    } \
 
 

In several places in my program I have the macro inserted as follows:

cout << "Some valid code";
FAULT
cout << "Some more valid code";

I want to be able to conditionally compile-in the macro FAULT if the variable "TESTME" is defined (i.e. it is provided at compile-time). Conversely, if TESTME is not defined then all instances of FAULT should be compiled out.

Most importantly- I want to be able to do this without changing all instances of FAULT as follows:

cout << "Some valid code";
#ifdef TESTME
FAULT
#endif
cout << "Some more valid code";

Here's what I already tried that didn't work:
1) Enclosing the macro itself within #ifdef-#endif
This causes the compiler to complain when it encounters instances of 'FAULT' in the code (since the macro definition no longer exists).

#ifdef TESTME
#define FAULT
    { \ 
          if (test.exists()) { \
              return error( "Aborting" ); \
          } \
    } \
#endif

2) I tried adding a #else clause to the macro defintion as follows. This did nothing.

#ifdef TESTME
#define FAULT
    { \ 
          if (test.exists()) { \
              return error( "Aborting" ); \
          } \
    } \
#else
#endif

3) I also tried enclosing the contents of the macro within a #ifdef-#endif as follows. This didn't compile either.

#define FAULT
    { \ 
#ifdef TESTME \
          if (test.exists()) { \
              return error( "Aborting" ); \
          } \
#endif \
    } \

I'll really appreciate any other ideas!

[weaknessforcats]

The onhe thing you didn't try was:

#ifdef TESTME
#define FAULT
    { \ 
          if (test.exists()) { \
              return error( "Aborting" ); \
          } \
    } \
#else
   #define FAULT
#endif
 

So if you are not testing FAULT is defined but has no defined value. So nothing is expanded.

[Matthew Page]

You might try adding another definition for FAULT in the else clause... That way in either case you get a definition for FAULT.

[yasmin]

Thanks, that really helped!

The onhe thing you didn't try was:

#ifdef TESTME
#define FAULT
    { \ 
          if (test.exists()) { \
              return error( "Aborting" ); \
          } \
    } \
#else
   #define FAULT
#endif
 

So if you are not testing FAULT is defined but has no defined value. So nothing is expanded.