I wrote about it in my repository, but I'll try to summarize it here: Protobuf is full of bad ideas. One such bad idea is that message fields are allowed to repeat and that the last field wins. So, if you were to write a SAX parser, you'd have a dilemma with how to handle this bizarre idea: do you accept that a callback for some property might be triggered multiple times or do you read the whole message ahead of time and then call callbacks exactly once for each property? If we accept that the parser must be lazy, we "solve" this problem by allowing the parser to read ahead (it needs to do this anyways), but this is a wasteful way to parse (uses more memory than necessary).
> The important part of protobuf is the spec of the wire format. That is what makes the standard an interop format.
I'm not sure what are you trying to say here. All messaging formats are made up of... wire format, that's what they are for. Maybe I'm not seeing it?
> Personally I also prefer code generation over dynamic parsers and generators.
I think you are trying to say that you prefer source code generation over generating supporting definitions at runtime? I wasn't talking about dynamic parser generation (eg. Lark). In my case, the parser was hand-written (using Bison + Flex) and compiled ahead of time, but the Python definitions supporting the Protobuf IML were generated at runtime.
If my guess is true, I'd like to hear your arguments in favor of generating Python source code that translates Protobuf IML into Python. To me it looks like a waste of space on disk... I really can't think of any reason to want that.