Seems fine to me.
One point: Rather than use ListFields(), I would recommend adding a type ID
field to Message, e.g.:
message Message {
optional int32 type_id = 1;
extensions 5 to max;
}
Reflection is kind of annoying to use, and can be somewhat slow.
On Thu, Nov 25, 2010 at 5:15 AM, Benoit Laurent laurent...@gmail.comwrote:
Hi,
I've done some experiment using protocol buffers extension but I kind
of wondering if I am doing things the right way. For the encoding I've
seen some explanation on the multi message encoding, and what I am
doing seems ok. On the other hand I am kind of suspicious about my
decoding routine.
my .proto file is pretty straightforward
message Message {
extensions 5 to max;
}
message Dummy {
optional float x = 1;
optional float y = 2;
}
message Foo {
optional int v = 1;
}
extend Message {
optional Dummy dummy = 5;
}
extend Message {
optional Foo foo = 50001;
}
My encoding code look like :
int fd = open(argv[1], O_CREAT|O_RDONLY|O_WRONLY);
google::protobuf::io::ZeroCopyOutputStream* raw_output = new
google::protobuf::io::FileOutputStream(fd);
google::protobuf::io::CodedOutputStream* coded_output = new
google::protobuf::io::CodedOutputStream(raw_output);
ns_message::Message message;
ns_message::Dummy* dummy =
message.MutableExtension(ns_message::dummy);
dummy-set_x(5);
int size = message.ByteSize();
coded_output-WriteVarint32(size);
message.SerializeToCodedStream(coded_output);
message.ClearExtension(ns_message::dummy);
ns_message::Foo* zoom = message.MutableExtension(csi_message::zoom);
[encoding the same way]
For the decoding here is what I am doing:
int fd = open(argv[1], O_RDONLY);
google::protobuf::io::ZeroCopyInputStream* raw_input = new
google::protobuf::io::FileInputStream(fd);
google::protobuf::io::CodedInputStream* coded_input = new
google::protobuf::io::CodedInputStream(raw_input);
ns_message::Message message;
google::protobuf::uint32 size;
while ( coded_input-ReadVarint32(size) ) {
int previous = coded_input-PushLimit(size);
message.ParseFromCodedStream(coded_input);
coded_input-PopLimit(previous);
std::vectorconst google::protobuf::FieldDescriptor* fields;
const google::protobuf::Reflection* reflection =
message.GetReflection();
reflection-ListFields(message, fields);
for (int i = 0; i fields.size(); ++i) {
if (fields[i]-is_extension()) {
getExtensionMessage(message, fields[i]);
}
}
}
getExtensionMessage doesn't do anything fancy for the moment
if(field-name() == dummy) {
csi_message::* Dummy = dummy.MutableExtension(ns_message::dummy);
print(*dummy);
}
Thanks in advance for your comments.
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