I’m developing static checker, so all modules need to be compiled first, before analysed.
For example, the @description attribute can either be set to a string, or otherwise refer to another function (which I can process later on).
# A.ex
defmodule A do
use B
@description "function1/0 returns :ok"
def function1() do
:ok
end
@description A.function1
def function2() do
:ok
end
end
# B.ex
defmodule B do
defmacro __using__(_) do
quote do
import B
Module.register_attribute(__MODULE__, :description, accumulate: true, persist: true)
Module.register_attribute(__MODULE__, :test, accumulate: true, persist: true)
@after_compile B
end
end
def __on_definition__(env, _access, name, args, _guards, _body) do
IO.puts("Reached on_definition")
desc = Module.get_attribute(env.module, :description) |> hd()
Module.delete_attribute(env.module, :description)
Module.put_attribute(env.module, :test, {name, length(args), desc})
end
def __after_compile__(_env, bytecode) do
IO.puts("Reached after_compile")
# Gets debug_info chunk from BEAM file
chunks =
case :beam_lib.chunks(bytecode, [:debug_info]) do
{:ok, {_mod, chunks}} -> chunks
{:error, _, error} -> throw("Error: #{inspect(error)}")
end
# Gets the (extended) Elixir abstract syntax tree from debug_info chunk
dbgi_map =
case chunks[:debug_info] do
{:debug_info_v1, :elixir_erl, metadata} ->
case metadata do
{:elixir_v1, map, _} ->
# Erlang extended AST available
map
end
x ->
throw("Error: #{inspect(x)}")
end
dbgi_map[:attributes]
|> IO.inspect
end
end
This outputs the following. &A.function1/0 is saved which is what was needed:
[description: "function1/0 returns :ok", description: &A.function1/0]
Compared to the Elixir module, you can set functions directly @callback foo. Can something cleaner (without the &a/0) be achieved?
