AtomEnforcer

AtomEnforcer exists to solve a problem encountered in production code- preventing run-time errors for mismatched atoms between sends and receieves, especially in GenServer APIs and handle_((call|cast|info) function heads.

The strategy is to explicitly allow certain atoms to exist within a module, and then, at compile time, raise an error if an atom is used which has not been allowed.

Getting Started

1. add {:atom_enforcer, "~> 0.1"}, to your mix.deps
2. add use AtomEnforcer, allowed_atoms: <atoms you want to use> to a module
3. find your atom typos at compile time now

API

The only API for AtomEnforcer is the __using__ macro and it's options:

• allowed_atoms: a single atom or a list of atoms which are allowed to exist in this module.
• allow_common: (default true) automatically whitelists [:ok, :error, true, false, nil]
• infer_genserver: (default true) If the module is a GenServer, automatically whitelists atoms used in genserver callbacks. See documentation for the full list.

Salient Example

#TODO: improve this example 
defmodule SomeGenServer do
  use GenServer
  use AtomEnforcer, allowed_atoms: [:api_call_1]

  def start_link([]) do
    GenServer.start_link(__MODULE__, [], [name: __MODULE__])
  end

  def api_call_1(args) do
    GenServer.call(__MODULE__, {:api_call_1, args}) 
  end

  def init([]), do: {:ok, []}

  # The misspelling on the next line will cause a CompileError to be thrown
  def handle_call({:ap_call_1, args}, _from, state) do
    {:reply, args, state}
  end

end

Closing Comments

Please drop me a note if you end up using AtomEnforcer in something cool, or file an issue if you have difficulty, bugs, or ideas for a better API.