How to generate python class files from protobuf

As of now, nothing like that is available. You might want to follow this issue: https://github.com/google/protobuf/issues/2638 to be up to date.

If you are using a recent Python (3.7+) then https://github.com/danielgtaylor/python-betterproto (disclaimer: I'm the author) will generate very clean Python dataclasses as output which will give you proper typing and IDE completion support.

For example, this input:

syntax = "proto3";

package hello;

// Greeting represents a message you can tell a user.
message Greeting {
  string message = 1;
}

Would generate the following output:

# Generated by the protocol buffer compiler.  DO NOT EDIT!
# sources: hello.proto
# plugin: python-betterproto
from dataclasses import dataclass

import betterproto


@dataclass
class Hello(betterproto.Message):
    """Greeting represents a message you can tell a user."""

    message: str = betterproto.string_field(1)

In general the output of this plugin mimics the *.proto input and is very easy to read if you happen to jump to definition on a message or field. It's been a huge improvement for me personally over the official Google compiler plugin, and supports async gRPC out of the box as well.