IRB Like Output in Pry

22 May 2014

Lately, I’ve been working through the excellent Understanding Computation book. It’s been fun. However, I am using Pry and the author’s examples use IRB so my REPL output is just different enough to get on my nerves. Luckily, Pry is extremely configurable through its .pryrc file. The following .pryrc line will make Pry output an object’s inspect method results, just like IRB.

Pry.config.print = proc { |output, value| output.puts "=> #{value.inspect}" }

Even better, Pry supports loading a per-directory .pryrc file so I can make this change in my project folder and avoid changing my settings globally.

Default Output

[1] pry(main)> Add.new(
[1] pry(main)*   Multiply.new(Number.new(1), Number.new(2)),
[1] pry(main)* Multiply.new(Number.new(3), Number.new(4)) )
=> #<struct Add
 left=
  #<struct Multiply
   left=#<struct Number value=1>,
   right=#<struct Number value=2>>,
 right=
  #<struct Multiply
   left=#<struct Number value=3>,
   right=#<struct Number value=4>>>
[2] pry(main)> Number.new(5)
=> #<struct Number value=5>

With `inspect` Output

[1] pry(main)> Add.new(
[1] pry(main)*   Multiply.new(Number.new(1), Number.new(2)),
[1] pry(main)* Multiply.new(Number.new(3), Number.new(4)) )
=> «1 * 2 + 3 * 4»
[2] pry(main)> Number.new(5)
=> «5»

Much better, right?

Default Output

With inspect Output

With `inspect` Output