Iex pry going step by step?

Question

I want to use IEx.pry to go step by step in my elixir code, like byebug in ruby or debug point in Java. I tried looking into the documentation here : https://github.com/elixir-lang/elixir/blob/4f68c4f10502e0f54a21093bb9a33957e63a9ac4/lib/iex/lib/iex.ex but did not find anything. Could anyone suggest a way to do this ?

Maybe you will find this useful: https://github.com/qhool/quaff — Patrick Oscity, Oct 18 '15 at 22:09
@PatrickOscity, I usually work on a remote machine. Is there a way to run the quaff tool in command line only ? — VoodooChild, Oct 31 '15 at 22:23
@VoodooChild: You can use `ssh -Y` when you ssh into your remote machine so any window will be redirected to your host machine. — Batou99, Oct 07 '16 at 05:56

score 15 · Answer 1 · answered Oct 20 '15 at 10:49

15

It is not possible as pry is not a debugger. Pry simply allows you to interact with a particular context.

answered Oct 20 '15 at 10:49

José Valim

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If pry isn't the answer to setting a breakpoint and stepping through a running Elixir program, what is? – sma Feb 17 '16 at 20:12
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@sma , as Patrick pointed out, github.com/qhool/quaff is a tool which you can use – VoodooChild Feb 18 '16 at 08:02
Can't believe I did not know about quaff until now. Thansk @sma – Steve Pallen Apr 26 '17 at 02:07

score 1 · Answer 2 · answered Mar 10 '18 at 10:37

I was hoping for a way to step through Elixir code via IEx.pry as well, but that's not possible. Erlang does have a debugger that you can use for Elixir code.

You can start the debugger by running: :debugger.start()

I learned about it here: http://blog.plataformatec.com.br/2016/04/debugging-techniques-in-elixir-lang/

score 1 · Answer 3 · edited Dec 20 '22 at 12:04

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As the other answers pointed out, pry does not offer this functionality.

As a workaround you could add multiple IEx.pry instructions, inspect and use continue to go to the next one.

edited Dec 20 '22 at 12:04

mit

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answered May 28 '20 at 06:59

samidarko

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`continue` is used to continue the execution, the question is about `step` functionality. – Daniel May 28 '20 at 07:42

score 0 · Answer 4 · answered Aug 25 '23 at 17:26

After elixir 1.14, you can use the next/0 function after setting a breakpoint on the function you wanna debug.

To se a breakpoint you need to enter your iex terminal and use the function break!/2 and pass the function and the arity, so said function receives a breakpoint. Like this:

break! MyModule.function_to_be_debugged/2

And then, when you call said function, you will be able to debug it, line by line with the next/0

Iex pry going step by step?

4 Answers4