How do I drop to the IRB prompt from a running script?

Question

Can I drop to an IRB prompt from a running Ruby script?

I want to run a script, but then have it give me an IRB prompt at a point in the program with the current state of the program, but not just by running rdebug and having a breakpoint.

horseyguy · Answer 1 · 2014-09-08T05:52:25.650

Pry (an IRB alternative) also lets you do this, in fact it was designed from the ground up for exactly this use case :)

It's as easy as putting binding.pry at the point you want to start the session:

require 'pry'
x = 10
binding.pry

And inside the session:

pry(main)> puts x
=> 10

Check out the website: http://pry.github.com

Pry let's you:

drop into a session at any point in your code
view method source code
view method documentation (not using RI so you dont have to pre-generate it)
pop in and out of different contexts
syntax highlighting
gist integration
view and replay history
open editors to edit methods using edit obj.my_method syntax

A tonne more great and original features

Thanks a lot, this should the at the top, I was on my way to use IRB for that — Dorian, Aug 23 '12 at 21:31

score 29 · Accepted Answer · answered Jul 17 '09 at 17:23

29

you can use ruby-debug to get access to irb

require 'rubygems'
require 'ruby-debug'
x = 23
puts "welcome"
debugger
puts "end"

when program reaches debugger you will get access to irb.

answered Jul 17 '09 at 17:23

Subba Rao

10,576
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Will this take the binding context into account? Can I set the binding to something else? – John F. Miller Sep 05 '09 at 01:35
2

This requires the `ruby-debug` gem, which doesn't work with Ruby 1.9. – Zr40 Jun 20 '12 at 12:53
1

for 1.9 you can use ruby-debug19 or the debugger gem http://stackoverflow.com/questions/8087610/ruby-debug-with-ruby-1-9-3 – rogerdpack May 28 '13 at 14:07

rogerdpack · Answer 3 · 2016-05-30T23:02:03.190

apparently it requires a chunk of code to drop into irb.

Here's the link (seems to work well).

http://jameskilton.com/2009/04/02/embedding-irb-into-your-ruby-application


require 'irb'

module IRB
  def self.start_session(binding) # call this method to drop into irb
    unless @__initialized
      args = ARGV
      ARGV.replace(ARGV.dup)
      IRB.setup(nil)
      ARGV.replace(args)
      @__initialized = true
    end

    workspace = WorkSpace.new(binding)

    irb = Irb.new(workspace)

    @CONF[:IRB_RC].call(irb.context) if @CONF[:IRB_RC]
    @CONF[:MAIN_CONTEXT] = irb.context

    catch(:IRB_EXIT) do
      irb.eval_input
    end
  end
end

Excellent find, thanks! This is exactly what I needed to access the class and instance variables in the context of where I invoked IRB.start_session(binding). — csmosx, Jul 29 '10 at 21:10

Tachyons · Answer 4 · 2017-07-19T11:56:31.240

This feature is available from Ruby 2.4. You can just use binding.irb

E.g.

require 'irb'
a = 10
binding.irb
puts a

If you run above code, you will get irb console, so that you can inspect values of local variables and anything else that is in scope.

Source: http://blog.redpanthers.co/new-binding-irb-introduced-ruby-2-4/

Ruby commit: https://github.com/ruby/ruby/commit/493e48897421d176a8faf0f0820323d79ecdf94a

Yuming Cao · Answer 5 · 2014-11-01T19:53:04.293

0

Just add this line to where you want the breakpoint:

require 'ruby-debug';debugger

but i suggest use pry instead of irb, which is super handy, insert the following line instead:

require 'pry'; binding.pry

edited Nov 01 '14 at 19:53

answered Nov 01 '14 at 19:24

Yuming Cao

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1
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score 0 · Answer 6 · answered Feb 06 '18 at 19:57

0

I'm quite late to the game but if you're loading a script from within irb/pry already, a simple raise also works to pop you back out to the irb/pry prompt. I use this quite often when writing one off scripts within the rails console.

answered Feb 06 '18 at 19:57

spyle

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How do I drop to the IRB prompt from a running script?

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