Dynamically reading a Protobuf FileDescriptorSet file into Python message classes

read_proto_desc.py

#!/usr/bin/env python
"""
Read a serialized Protobuf FileDescriptorSet that was 
generated from the protoc tool, and dynamically generate
the python classes for each message.
"""
import sys

from google.protobuf import descriptor_pb2
from google.protobuf import reflection
from google.protobuf import symbol_database


def gen(desc_file, db=None):
	if not db:
		db = symbol_database.Default()

	with open(desc_file, 'rb') as fh:
		fds = descriptor_pb2.FileDescriptorSet.FromString(fh.read())

	generated = {}

	for prot in fds.file:
		fd = db.pool.Add(prot)
		for name in fd.message_types_by_name:
			mdesc = fd.message_types_by_name[name]
			Klass = reflection.MakeClass(mdesc)
			generated[(fd.package, name)] = db.RegisterMessage(Klass) 

	return generated


if __name__ == '__main__':
	from pprint import pprint
	generated = gen(sys.argv[1])
	pprint(generated)