Question

I have the following 2 macros:

#define SCOPED_ENUM_HEADER(NAME) struct NAME{ enum _NAME{
#define SCOPED_ENUM_FOOTER(NAME) };}; typedef NAME::_NAME NAMEtype;

Only the first instance of NAME get replaced by the passed NAME. What’s wrong with it?

Is is to be used in such a way:

 SCOPED_ENUM_HEADER(LOGLEVEL)
   UNSET,
   FILE,
   SCREEN
 SCOPED_ENUM_FOOTER(LOGLEVEL)

Answer 1

The problem is that NAME is not the same as _NAME; they are two totally separate identifiers.

If you want to add an underscore to the front of whatever the parameter NAME is, use the concatenation (##) operator:

_##NAME

You do need to be really careful with prepending an underscore, though. All identifiers beginning with an underscore followed by a capital letter are reserved to the implementation.