23Skidoo / protobuf_compiler

Provides a compiler task for using protobuf in elixir projects

ProtobufCompiler

Provides a mix task mix compile.proto for easier integration of elixir-protobuf/protobuf.

The task will:

1. Fetch options, gather .proto sources
2. Check the protoc binary exists and is executable
3. Check the protoc-gen-elixir plugin is available and executable
4. Ensure the target directory exists
5. Check if any of the sources are "stale"
6. Compile each file replacing the basename .proto with .pb.ex

Installation

If available in Hex, the package can be installed by adding protobuf_compiler to your list of dependencies in mix.exs:

def deps do
  [
    {:protobuf, "~> 0.9.0"},
    {:protobuf_compiler, "~> 0.2.0"}
  ]
end

Protoc options can be set in the project:

defmodule MyProject.MixProject do
  use Mix.Project

  def project do
    [
      app: :my_project,
      ...
      protoc_opts: [
        paths: ["lib"],
        dest: "lib/protobuf/",
        gen_descriptors: true 
      ]
    ]
  end

Module prefix

defmodule MyProject.MixProject do
  use Mix.Project

  def project do
    [
      app: :my_project,
      ...
      protoc_opts: [
        ...
        package_prefix: "Custom"
      ]
    ]
  end

Your modules will now be generated with a namespace:

defmodule Custom.Example do
  @moduledoc false
  use Protobuf, syntax: :proto2
  @type t :: %__MODULE__{}

  defstruct []
end

Plugin Version

There is a strict dependency between protobuf library version and plugin used for code generation.

This compiler tries to install the best suited plugin version:

• if protobuf is a dep in your application, plugin is built from sources; else
• if protoc-gen-elixir is found in your PATH, it will be used (mostly intended to developers); else
• compiler uses mix escript.install hex to install prebuilt version of the plugin.

When not built from source, you can force a specific version of the plugin with the config:

config :protobuf_compiler, plugin_version: "0.8.0"

Documentation

Documentation can be generated with ExDoc and published on HexDocs. Once published, the docs can be found at https://hexdocs.pm/protobuf_compiler.