尝试了monad模式，但仍然有重复的错误处理

Question

I read Rob Pike's post but it only works for repetitive loops. I, on the other hand, have this. Notice how I added the err field, accessible via the Error() method, in a futile attempt to reduce the if errs.

The code above is simpler, but the ReadRLP() function is no different from just returning a err. Is there some pattern that can help with this?

type namePreclaimRLP struct {
    ObjectTag         uint
    RlpMessageVersion uint
    AccountID         []uint8
    AccountNonce      uint64
    CommitmentID      []uint8
    Fee               big.Int
    TTL               uint64
    err               error
}

func (n *namePreclaimRLP) ReadRLP(s *rlp.Stream) (aID, cID string) {
    blob, err := s.Raw()
    if err != nil {
        n.err = err
    }
    err = rlp.DecodeBytes(blob, n)
    if err != nil {
        n.err = err
    }
    _, aID, err = readIDTag(n.AccountID)
    if err != nil {
        n.err = err
    }
    _, cID, err = readIDTag(n.CommitmentID)
    if err != nil {
        n.err = err
    }
    return aID, cID
}

func (n *namePreclaimRLP) Error() (err error) {
    return n.err
}

Answer 1

Your code doesn't compile as written (there are a lot of missing types), so I can't fully test this code, but I would expect something along these lines, returning err in the typical Go approach, rather than making it part of another type, which is unusual and a bit confusing:

func (n *namePreclaimRLP) ReadRLP(s *rlp.Stream) (aID, cID string, err error) {
    var blob SomeType // Depends on what blob actually is
    if blob, err = s.Raw(); err != nil {
        return
    }

    if err = rlp.DecodeBytes(blob, n); err != nil {
        return
    }

    if _, aID, err = readIDTag(n.AccountID); err != nil {
        return
    }

    _, cID, err = readIDTag(n.CommitmentID)

    return
}

I'd delete your Error() function here and the err field. namePreclaimRLP is not a kind of error. It feels you're abusing the interface there.