Comments in textual serialized protobuf? (not the scheme definition)

Question

I'm using textual protobuf files for system configuration.
One problem I have with this is that the serialized protobuf format does not support comments.
Is there any way around this?
I'm talking about the textual serialized data format, not the scheme definition.
Was this problem solved somewhere by someone?

Answer 1

Textual Protobuf format (serialized protobuf messages in text formal) supports comments using the # syntax. I could not find a reference for the same in any online documentation but have used the same in projects in the past so I put together a small example that one can test with:

Sample message description - [SampleProtoSchema.proto]

message SampleProtoSchema {
  optional int32 first_val = 1; // Note: This supports C/C++ style comments
  optional int32 second_val = 2;
}

Sample text message - [SampleTextualProto.prototxt]

# This is how textual protobuf format supports comments
first_val: 12 # can also be inline comments
# This is another comment
second_val: 23

Note though that these comments cannot be generated automatically at time of serialization. They can only be added manually afterwards.
Compile and test:

> protoc --python_out=. SampleProtoSchema.proto
>
> ipython
[1]: import SampleProtoSchema_pb2
[2]: sps = SampleProtoSchema_pb2.SampleProtoSchema()
[3]: from google.protobuf import text_format
[4]: with open('SampleTextualProto.prototxt', 'r') as f:
         text_format.Merge(f.read(), sps)
[5]: sps.first_val
[5]> 12
[6]: sps.second_val
[6]> 23