Yes - my response is to the suggestion that casting between pointers to functions of different signature is undefined. I took this to be a suggestion that the p

Yes - my response is to the suggestion that casting between pointers to functions of different signature is undefined. I took this to be a suggestion that the part of the approach that involves having a general-purpose function that can accept a pointer to any kind of function, and reliably use that pointer (after it's been casted, if necessary) to get a pointer to the function in question, is fundamentally non-portable. I remain unconvinced that this is a serious issue, all things considered. The odd feeling that there could be other roadblocks to a fully portable implementation still remains. Nevertheless, it appears that this particular part could actually be done portably.