Passing a template which requires a comma to a single-argument macro

Question

I have some code that essentially condenses down to

#define FOO(a)
FOO(std::map);

But it emits a compile error (too many ac

Answer 1

The comma is being treated as a macro argument seperator, it does not do this with commas within parenthesizes.

If you are using Boost, they provide BOOST_PP_COMMA:

#include 

#define FOO(a)
FOO(std::map);

You can also define your own:

#define COMMA ,
FOO(std::map);