On Mon, Jun 8, 2015 at 7:43 AM, Colin Deasy <cde...@demonware.net> wrote:
> Hey, > > When reading > https://developers.google.com/protocol-buffers/docs/proto#simple I see a > stark warning indicating that "Required is Forever" advocating the use of > optional with additional application level validation routines. This is > because if at some point a required field is no longer written, the readers > will break. > > However IMO, there are common cases where 'required' is a good thing - > given that it's enforced only during encoding/decoding. > For example there may be some field that is 'required' (right now) to both > the reader and writer. Even if that changes at some point in the future to > become optional, the reader would likely have to be updated regardless of > the protocol decoding routine as it may make assumptions (reasonable > considering it was required in the first place) on the presence of the > field (e.g. the field being a key to a certain bit of data). In this case > the approach would be to update the .proto of all readers to make that > field optional, followed by updating all writers to remove the field. > In simpler scenarios, yes, it's possible to migrate a required field to optional even though it's an incompatible change, but in a more complicated system, where you have many different binaries using the same proto file running on thousands of machines, it's hard to tell whether all readers of a proto has been updated or not. You have to be very careful with such changes, and if you miss one, bad things can happen. > Given this, I feel that the current language of the linked document gives > the impression that the 'required' attribute is a Bad Thing and should be > avoided. I hope you can clarify if I'm missing some crucial bit of > information regarding it's usage. > > Thanks > Colin > > -- > You received this message because you are subscribed to the Google Groups > "Protocol Buffers" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to protobuf+unsubscr...@googlegroups.com. > To post to this group, send email to protobuf@googlegroups.com. > Visit this group at http://groups.google.com/group/protobuf. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Protocol Buffers" group. To unsubscribe from this group and stop receiving emails from it, send an email to protobuf+unsubscr...@googlegroups.com. To post to this group, send email to protobuf@googlegroups.com. Visit this group at http://groups.google.com/group/protobuf. For more options, visit https://groups.google.com/d/optout.
