Hi Johan, Thanks a lot for the comments, and the independent implementation!
> - For the opcode parameter ordering, it feels unnatural for the two > tweaks (data, taptree) to be separated by the internal key. A more > natural ordering of parameters IMO would be (of course this is all > subjective): > <data> <taptree> <internalkey> <index> <flags> OP_CCV. > > If you disagree, I would love some rationale for the ordering you > chose! (looks like you also changed it again after your last post?). The main concern for the reordering was to put <data> at the bottom, as that's typically passed via the witness stack. I put the <index> right next, as I suspect there are use cases for specifying via the witness what is the input index where a certain (CCV-encumbered) UTXO is to be found, or which output should funds be sent to, instead of hard-coding this in the script. This might help in designing contracts that are more flexible in the way they are spent, for example by allowing batching their transactions. Instead, I expect the other parameters to almost always be hardcoded, or propagated from the current input with the <-1> special values. I agree that your ordering is more aesthetically pleasing, though. > I'm wondering what other use cases you had in mind for the deferred > output amount check? Maybe I have missed something, but if not it > would perhaps be better to leave out the amount preservation check, or > go the extra mile and propose a more powerful amount introspection > machinery. Yes, the deferred output amount check is not enough for coinpools; however, it comes at no cost if we have a <flags> parameter anyway, as OP_2 (value for CCV_IGNORE_OUTPUT_AMOUNT) is a single byte opcode. The intent of preserving amounts for many-to-one contracts (vaults), or the one-to-one cases (channels, any 2-party contract, etc.) seems common enough to deserve 1 bit in the flags, IMHO. Efforts to define and add explicit introspection to cover your (exciting!) use cases can proceed independently, but I don't think they would nullify the advantages of this (optional) feature of CCV. Best, Salvatore
_______________________________________________ bitcoin-dev mailing list bitcoin-dev@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
