Add support to hook into require

[Papipo]

Hi!

I have this app in which users can provide their lua scripts. I don't have those in the filesystem so I need to intercept require calls somehow (I will be returning them from the database or as chunks from ETS).

An option is to override require itself, but I think that adding a searcher after the preload one is more lua-esque.

In case it's better to just override require, how would yo approach returning preloaded modules?
Basically I don't know if luerl provides a mechanism to hook into require and if we can wrap it in this lib.

Thanks!

[Papipo]

Alternatively, creating a separate function (ie. import) that works like require but allows to return modules, that's also fine.

[Papipo]

This works, I can return anything from the imported script:

defmodule ErluaTest do
  use ExUnit.Case
  doctest Erlua
  import Lua

  defmodule Custom do
    @imports %{
      "custom" => ~LUA"""
        return {
          greet = function(name)
            print("Printed hello, " .. name)
          end,
          template = function(name)
            return "Templating hello, " .. name
          end
      }
      """
    }

    def import([], [path], state) do
      {:ok, ret, state} = Luerl.New.do(state, @imports[path])
      {ret, state}
    end
  end

  test "Loading lua scripts dynamically" do
    entrypoint = ~LUA"""
      print("I am the entrypoint")
      local imported = import("custom")
      imported.greet("world")
      print("gonna print a rendered template: " .. imported.template("world"))
    """

    result =
      Lua.new()
      |> Lua.set!([:import], {Custom, :import, []})
      |> Lua.eval!(entrypoint)
  end
end

But as you can see I had to use Luerl do, you can't use eval! there.
Also, conceptually I don't know if the import function should reuse the state or use a blank slate. I like the latter to avoid unexpected side effects.

[davydog187]

Hello @Papipo, I'm still thinking about ways to do this. I'll get back to you