Hi Branislav, Thanks for the feedback.
This is a frequent request for protobuf and Cap'n Proto. Presumably the compiler would automatically number the fields in the order they appear. My concern is that in this mode, it is very easy to accidentally introduce backwards-incompatibility by inserting a field into the middle of the struct, or by re-ordering field declarations during refactoring. I think it would be non-obvious to many developers that the ordering of field declarations mattered -- many developers assume that fields are identified on the wire by name, by sending the schema, or by some other magic. Such accidents likely wouldn't be caught in automated testing since it's unusual to test compatibility with binaries built with different versions of the protocol, and they wouldn't be caught in review since reviewers may be similarly confused about the importance of the field ordering. Meanwhile I think that if we made field numbers optional, most developers would in fact omit them, since developers tend to take the path of least resistance. OTOH, with field numbers being required, the path of least resistance is actually pretty robust. Most developers will infer that the numbers are probably important for something, and than renumbering fields is likely to be a bad idea, even if they don't know exactly what they are for. In my experience, it is remarkably uncommon for people to accidentally make backwards-incompatible changes in Protobuf or Cap'n Proto, which is a great thing. -Kenton On Tue, Jul 25, 2017 at 6:10 AM, Branislav Katreniak <katren...@gmail.com> wrote: > When prototyping capnproto structs, I feel a bit of burden to make the > compiler happy to assign valid numbers to all fields. > > What about having and option to let the compiler generate the sequence > numbers automatically if the field number is not assigned to any field? > > Flatbuffers IDL works this way. > > -- > You received this message because you are subscribed to the Google Groups > "Cap'n Proto" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to capnproto+unsubscr...@googlegroups.com. > Visit this group at https://groups.google.com/group/capnproto. > -- You received this message because you are subscribed to the Google Groups "Cap'n Proto" group. To unsubscribe from this group and stop receiving emails from it, send an email to capnproto+unsubscr...@googlegroups.com. Visit this group at https://groups.google.com/group/capnproto.
