I don't pretend to know the original thinking, but it would be very hard to add such now without breaking existing clients. However, note that if you *really* don't want to have to get the lengths, you could encode your data inside a "group", since this has a terminator rather than a length prefix. Treat the data as a "repeated" set of the group, and job done.
Of course, writing the length isn't usually a massive task either, but *not* writing it is easier :p Caveat: technically groups are semi-deprecated, giving preference to length-prefixed messages. I believe that part of the reasoning here is the higher cost of reading *unexpected* groups since you must parse the stream rather than just copy (or skip) the next [n] bytes, but in my *own* use of protobuf this is rarely an issue: in the majority of cases all my clients know about the fields. There is also a difference in the size, but "difference" is the key term here - neither approach is always longer or always shorter; any comparison depends on both the field number and the size of the data. I openly confess to having a strong like for "groups" - they do make the encoding process simpler :p Marc On 7 Jul 2011, at 14:18, nicolas hofmann <hofmann....@gmail.com> wrote: > My question is simple but i didn't found the answer anywhere. I was > wondering why the tag number range started at one and not zero. > > I was looking for a way to stream multiple messages without having to > compute their sizes and realized that just add a zero tag number at > the end could be a good way to mean the end of the current message > since it's illegal. I searched here and in the > documentation(especially in the encoding section) but saw no good > reason to this limitation. > > It look so simple i think I'm probably missing something but, by > definition, i don't know what. > > > Thanks,... > > -- > You received this message because you are subscribed to the Google Groups > "Protocol Buffers" group. > To post to this group, send email to protobuf@googlegroups.com. > To unsubscribe from this group, send email to > protobuf+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/protobuf?hl=en. > -- You received this message because you are subscribed to the Google Groups "Protocol Buffers" group. To post to this group, send email to protobuf@googlegroups.com. To unsubscribe from this group, send email to protobuf+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/protobuf?hl=en.
