dev.livemd

Debugger

import Codex.KinoHelpers

Section

{:ok, pid} = Entrace.start_link()
Entrace.trace_cluster(pid, {Play, :add, 2}, &IO.inspect/1)

# this was not working
Codex.KinoHelpers.trace({Play, :add, 2})

entrace.exs

{:ok, pid} = Entrace.start_link()
Entrace.trace_cluster(pid, {Play, :add, 2}, &IO.inspect/1)

kino_helpers.ex

defmodule Codex.KinoHelpers do
  def trace(mfa) do
    {:ok, tracer} = Entrace.start_link()
    trace_frame = Kino.Frame.new()
    trace(tracer, trace_frame, mfa)
    trace_frame
  end

  def trace(tracer, trace_frame, mfa) do
    Entrace.stop(tracer, mfa)

    Entrace.trace(tracer, mfa, fn %Entrace.Trace{} = t ->
      IO.inspect(t)

      {_mod, _fun, args} = t.mfa

      [stack_item | _rest] = t.stacktrace

      columns = [
        Kino.Text.new(format_stacktrace_item(stack_item)),
        Kino.Tree.new(args)
      ]

      columns =
        if t.returned_at != nil do
          {:return, ret} = t.return_value
          columns ++ [format_return(ret)]
        else
          columns
        end

      stack =
        for {mod, fun, arity, [file: _file, line: _line]} <- t.stacktrace do
          [func: format_mfa({mod, fun, arity})]
        end

      Kino.Frame.append(
        trace_frame,
        Kino.Layout.tabs(
          Summary: Kino.Layout.grid(columns, columns: Enum.count(columns)),
          Stacktrace: Kino.DataTable.new(stack)
        )
      )
    end)
  end

  def format_stacktrace_item({:elixir, :eval_external_handler, _, _}) do
    "(eval)"
  end

  def format_stacktrace_item({mod, fun, arity, [file: file, line: line]}) do
    format_mfa({mod, fun, arity}) <> " " <> "#{file}:#{line}"
  end

  def format_mfa({mod, fun, arity}) do
    "Elixir." <> mod_name = Atom.to_string(mod)
    "&#{mod_name}.#{fun}/#{arity}"
  end

  def format_mfa(bad_mfa) do
    inspect(bad_mfa)
  end

  defp format_return(v) when is_binary(v) or is_number(v) or is_atom(v) do
    Kino.Inspect.new(v)
  end

  defp format_return(v) do
    Kino.Tree.new(v)
  end
end