Personally I prefer using attributes instead of pragmas.  The GCC manual recommends such as well.  There are also other sources in Modules/* that use '__attribute__ ((visibility ("hidden")))'.  Namely ctypes and zlib.

I can understand that it is more work, but I find something like the following more readable (I am not actually suggesting names here, just an example):

   #define PY_LOCAL __attribute__ ((visibility ("hidden")))

   ...

   void foo(void) PY_LOCAL;
   void bar(void) PY_LOCAL;