A tool for generating Mypy type stubs from a Protocol Buffer definition.
You can download a binary from the releases page, or you can use Docker.
Assuming that you have a .proto file called foo.proto and you want to
generate a .pyi file from it, usage is as such:
protostub generate --proto foo.proto
In this case, protostub assumes you want to call your stub foo_pb2.pyi. If
this is not the case, or perhaps you want to specify a different directory, the
output can be specified like so:
protostub generate --proto foo.proto --mypy bar.pyi
Help is included in the tool:
Generate Mypy type stubs from Protobuf definitions
Usage:
protostub [command]
Available Commands:
generate Generate a stub from a given proto file
help Help about any command
Flags:
-h, --help help for protostub
Use "protostub [command] --help" for more information about a command.
If you've tried using mypy in your project, you've probably noticed that it does not do anything for protobuf types. This is because the generated python contains nothing that Mypy can use - classes are not defined in the "normal" way.
We currently use a script to generate a list of files for Mypy to check. If the
.py file has a corresponding .pyi file, then the .py is ignored. Otherwise
it is used. This allows us to override any Python with a type stub, meaning we
can override Python generated by protoc with something generated by protostub,
and get functioning type checks!
An alternative would be to invoke Mypy on a module rather than on files, and
provide the stubs in MYPYPATH. However, I have not tested this, so I don't know
how well it works.
A docker image is also provided! The easiest way for you to use this is as follows (assuming there is a file called foo.proto in the current directory):
docker run -v $(pwd):/protostub protostub:latest generate -p foo.proto
After doing this, you should see the help text.
- Go
- make (optional)
If you already have Go all setup in your PATH, then it is as simple as:
go get github.com/arachnys/protostub/cmd/protostub
This approach might be best if you're less familiar with Go, and want it to
just work. It requires no messing with $GOPATH.
git clone https://github.com/arachnys/protostub
cd protostub
make
The protostub binary should be in the bin folder.
Protostub was created and used internally at Arachnys before mypy-protobuf was released as an open source project. We use it as part of our CI to try and catch issues before they make it into production. As such, it's very important that everything is dockerized - hence it's on Docker hub, so there's no dependency on Python or protoc.
We also have out of the box Python 3 support, as that is what our codebase required.
Our version is also completely standalone, and does not function as a plugin for protoc. While this means you only need one binary (statically linked with no dependencies), it does mean that it may not be quite as "correct" in terms of parsing protobuffers, or generating python code.
The MIT License (MIT)
Copyright © 2018 Arachnys Information Services Ltd and individual contributors.
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the “Software”), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.