This feature was just implemented internally, and I believe it should make the next release (2.5.0). It's in progress, but not quite ready to hit svn yet.
On Thu, Aug 30, 2012 at 6:53 AM, Jan Koriťák <je...@pudr.com> wrote: > Hello, > > I am using Python to write a tool to control our backends which > communicate using protocol buffers. > > We would like our tool to be independent on current version of backends > and therefore independent on .proto files that were used to build the > particular version of the backend. > > Therefore the tool receives serialized FileDescriptorSet over network, > which should allow to create messages from the same descriptors, that are > used at the backend side. > > This is possible to implement in C++ (and we actually use it in another > component) using DynamicMessage. (Create DescriptorPool, load all the > FileDescriptors > to the pool using BuildFile(), and then retrieve Descriptor from the > pool. Then it is possible to create message using DynamicMessageFactory) > > However, after thorough research on the web and of the source code of > protocol buffers python bindings, I couldn't figure out how to do this > (version 2.4.0). > > I was able to deserialize FileDescriptorSet, iterate over FileDescriptorProtos > and get DescriptorProto object. However I didn't find a way to construct > Descriptor > objects, which are needed to create classes for message types(with > GeneratedProtocolMessageType > as a metaclass). > > I tried another way, when I found some access to C++ library API in > google.protobuf.internal (which is probably not a good idea to use). I > tried to indirectly use the C++ descriptor pool by cpp_message.BuildFile(), > but there is no way to get the Descriptor object back from the pool (it > would be C++ object anyway). However there is a method > cpp_message.NewCMessage, which can construct a message using descriptors > from the pool. I was able to construct messages that way, but I was unable > to set any fields. Only method that appeared usable was SetScalar, which > requires C++ decriptor, which I was unable to get. Not to mention all of > the Python magic is gone when dealing directly with the C++ API. > > Is there any way to create messages of arbitrary type, which is > distributed over network, in Python ? I see those possibilities in both > Java and C++, is Python library lacking such funcionality ? > > Thank you very much, hope I was clear enough. > Best regards,¨ > > Jan Koritak > > -- > You received this message because you are subscribed to the Google Groups > "Protocol Buffers" group. > To view this discussion on the web visit > https://groups.google.com/d/msg/protobuf/-/LEFgfPpImWEJ. > 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.
