example.c

#define GNUNET_MQ_hd_fixed_size(name,code,str,ctx)           \
  ({                                                         \
    void (*_cb)(void *cls, const str *msg) = &handle_##name; \
    ((struct GNUNET_MQ_MessageHandler) {                     \
      NULL, (GNUNET_MQ_MessageCallback) _cb,                 \
      (ctx), (code), sizeof (str) });                        \
  })

#define GNUNET_MQ_hd_var_size(name,code,str,ctx)             \
  ({                                                         \
    int (*_mv)(void *cls, const str *msg) = &check_##name;   \
    void (*_cb)(void *cls, const str *msg) = &handle_##name; \
    ((struct GNUNET_MQ_MessageHandler)                       \
      { (GNUNET_MQ_MessageValidationCallback) _mv,           \
        (GNUNET_MQ_MessageCallback) _cb,                     \
        (ctx), (code), sizeof (str) });                      \
  })