Rexerbug

An opinionated wrapper for Elixir trace debugging

What?

Rexbug wraps :redbug, providing a more Elixir-like syntax for trace debugging. But Rexbug isn't Elixir-y enough for me, so I made Rexerbug to wrap Rexbug.

Function tracing

Instead of passing a magic string to Rexbug, you pass code that will be parsed into a trace. For example:

# Rexerbug
Rexerbug.trace(&Map.new/1)

# Rexbug
Rexbug.start("Map.new/1 :: return;stack")

# redbug
:redbug.start('\'Elixir.Map\':new -> return;stack')

An installation of Rexerbug includes Rexbug, so its magic strings will still work.

Rexerbug.trace("String.starts_with?(_, \"a\") :: return")

Process tracing

When tracing processes, Rexbug requires a magic list instead of a magic string. I wanted to cut all that out and focus on the process to be traced:

myself = self()

process = Process.spawn(fn ->
  receive do
    msg -> send(myself, {:got, msg})
  end
end)

# Rexerbug
Rexerbug.monitor(process)

# Rexbug
Rexbug.start([:send, :receive], procs: [process])

Options

I've renamed some options toward more "expected" names. These are completely my own bias, but I think they make more sense. Here are the new names compared to the old. Shown values are the defaults, which have NOT changed from Rexbug to Rexerbug:

Rexerbug.trace(
  &Map.new/1,
  count: 10,
  timeout: 60_000,
  pids: :all,
  connect: Node.self(),
  arity?: false,
  buffer?: false,
  discard?: false
)

Rexbug.start(
  "Map.new/1 :: return;stack",
  msgs: 10,
  time: 60_000,
  procs: :all,
  target: Node.self(),
  arity: false,
  buffered: false,
  discard: false
)

Caveats

Because my wrapper is opinionated toward how I always use Rexbug, it has lost some flexibility. A return value of return;stack is assumed. Both :send and :receive events are assumed when monitor/2ing a process.

Installation

def deps do
  [
    {:rexerbug, "~> 1.0.0"}
  ]
end