Question

I’m trying to configure a simpler Pry prompt for entering Ruby code. What does nest_level mean? The Pry documentation says, “Three parameters are passed into the prompt procs, the object that is the target of the session, the current nesting level, and a reference to the associated Pry instance. These objects can be used in the prompt, if desired.” Their example is:

Pry.config.prompt = proc { |obj, nest_level, _| "#{obj}:#{nest_level}> " }

However, nest_level doesn’t seem to be what I think it is:

main:0> if true
main:0>   if true
main:0>     while true
main:0>       puts 1
main:0>       break
main:0>     end  
main:0>   end  
main:0> end  
1
=> nil
main:0> 

Answer 1

The nesting level refers the scope. In pry, you can use the cd command to “enter” objects, which is like using instance_eval – allowing you to use methods of said object without prefixing them with the object’s name. For example(with the same prompt proc you used):

main:0> arr=[1,2,3]
=> [1, 2, 3]
main:0> cd arr
[1, 2, 3]:1> first
=> 1
[1, 2, 3]:1> last
=> 3
[1, 2, 3]:1> count
=> 3
[1, 2, 3]:1> exit
=> [1, 2, 3]
main:0> 

I’ve cded into the array, and called it’s method without prefixing them with arr.. The nesting level was changed to 1 when I cded into it, and went back to 0 when I exited. I could also use cd .. to exit the scope.