[wruza]

What do you think of

  T get_t(int how, char **error);
  int get_val(T *v);

One could rewrite these as

  struct get_t_res {T; char *};
  struct get_t_res get_t(int);

  struct get_val_res {int; T};
  struct get_val_res get_val();

But what do you think of it?

[jacquesm]

Less clear. I much prefer for functions to do what's on the tin in the most simple way possible.