Debugging via IEx

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1

Hey!

I always find it a bit cumbersome to type require IEx; IEx.pry() whenever I need to debug something. Especially because of the lower and uppercase letters it is harder to type than for example binding.pry or byebug in Ruby.

So I figured I would create a helper function, like MyApp.pry():

defmodule MyApp do
  def pry() do
    require IEx
    IEx.pry()
  end
end

But obviously that won’t work since it will run IE.pry() inside the helper function instead of in the caller context.

So then I created this macro:

defmodule MyApp do
  defmacro pry() do
    quote do
      require IEx
      IEx.pry()
    end
  end
end

Unfortunately, now we’re back to square one though, since I’d still need to require MyApp; MyApp.pry().

So I finally settled on the following solution:

defmodule MyApp.Debugger do
  defmacro __using__(_opts \\ []) do
    quote do
      require IEx
      IEx.pry()
    end
  end
end

Which allows me to set a breakpoint anywhere using use MyApp.Debugger. Could even rename it to just use Debugger.

What do you think of this approach?

2 Likes
2

Why not just put the code you need to load in your .iex.exs file in the root project directory? :slight_smile:

1 Like
3

@OvermindDL1 how do you mean exactly?

4

Any lines you add to that file (as per the linked documentation) are run upon loading IEx, so you can require whatever you want, include whatever you want, make whatever variables you want, add whatever helpers you want, etc… etc… etc… :slight_smile:

It’s in the documentation I linked in that post. :slight_smile:

3 Likes
5

Hmm I don’t see how that would work in practice, for example if I put the following in .iex.exs:

require IEx
import IEx, only: [pry: 0]

… then I won’t be able to call pry in my module functions (undefined function pry/0).

6

I like this a lot. Can you please open up an issue in Elixir’s issues tracker? Make we could support use IEx.Pry as a built-in part of core and save everyone some precious typing.

2 Likes
7

@josevalim Sure: https://github.com/elixir-lang/elixir/issues/8125

That could be a nice improvement yes.