What the best ways to use decimals and datetimes with protocol buffers?

Question

I would like to find out what is the optimum way of storing some common data type that were not included in the list supported by protocol buffers.

• datetime (secon

Answer 1

Sorry, not a complete answer, but a "me too".

I think this is a great question, one I'd love an answer to myself. The inability to natively describe fundamental types like datetimes and (for financial applications) fixed point decimals, or map them to language-specified or user-defined types is a real killer for me. Its more or less prevented me from being able to use the library, which I otherwise think is fantastic.

Declaring your own "DateTime" or "FixedPoint" message in the proto grammar isn't really a solution, because you'll still need to convert your platform's representation to/from the generated objects manually, which is error prone. Additionally, these nested messages get stored as pointers to heap-allocated objects in C++, which is wildly inefficient when the underlying type is basically just a 64-bit integer.

Specifically, I'd want to be able to write something like this in my proto files:

message Something {
   required fixed64 time = 1 [cpp_type="boost::posix_time::ptime"];
   required int64 price = 2 [cpp_type="fixed_point"];
   ...
 };

And I would be required to provide whatever glue was necessary to convert these types to/from fixed64 and int64 so that the serialization would work. Maybe thru something like adobe::promote?