Question

I can start a pry session of a command line app like this

pry -r ./todo.rb

However, if I want to call the list function

pry -r ./todo.rb list 

I’m getting an error message.

Without pry, I call the list function

ruby todo.rb list

This is the error message

/Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@global/gems/pry-0.9.10/lib/pry/repl_file_loader.rb:16:in `initialize': No such file: /Users/michaeljohnmitchell/Sites/todo/bin/list (RuntimeError)
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@global/gems/pry-0.9.10/lib/pry/pry_class.rb:161:in `new'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@global/gems/pry-0.9.10/lib/pry/pry_class.rb:161:in `load_file_through_repl'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@global/gems/pry-0.9.10/lib/pry/cli.rb:162:in `block in <top (required)>'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@global/gems/pry-0.9.10/lib/pry/cli.rb:65:in `call'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@global/gems/pry-0.9.10/lib/pry/cli.rb:65:in `block in parse_options'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@global/gems/pry-0.9.10/lib/pry/cli.rb:65:in `each'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@global/gems/pry-0.9.10/lib/pry/cli.rb:65:in `parse_options'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@global/gems/pry-0.9.10/bin/pry:16:in `<top (required)>'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@global/bin/pry:19:in `load'
    from /Users/michaeljohnmitchell/.rvm/gems/ruby-1.9.2-p290@global/bin/pry:19:in `<main>'

Source Code

TODO_FILE = 'todo.txt'

def read_todo(line)
  line.chomp.split(/,/)
end

def write_todo(file,name,created=Time.now,completed='')
  file.puts("#{name},#{created},#{completed}")
end

command = ARGV.shift

case command
when 'new'
  new_task = ARGV.shift

  File.open(TODO_FILE,'a') do |file|
    write_todo(file,new_task)
    puts "Task added."
  end
when 'list'
  File.open(TODO_FILE,'r') do |file|
    counter = 1
    file.readlines.each do |line|
      name,created,completed = read_todo(line)
      printf("%3d - %s\n",counter,name)
      printf("      Created   : %s\n",created)
      unless completed.nil?
        printf("      Completed : %s\n",completed)
      end
      counter += 1
    end
  end
when 'done'
  task_number = ARGV.shift.to_i
  binding.pry

  File.open(TODO_FILE,'r') do |file|
    File.open("#{TODO_FILE}.new",'w') do |new_file|
      counter = 1
      file.readlines.each do |line|
        name,created,completed = read_todo(line)
        if task_number == counter
          write_todo(new_file,name,created,Time.now)
          puts "Task #{counter} completed"
        else
          write_todo(new_file,name,created,completed)
        end
        counter += 1
      end
    end
  end
  `mv #{TODO_FILE}.new #{TODO_FILE}`
end

Update

when I try

pry -r ./todo.rb -e list

I’m getting the following error

NameError: undefined local variable or method `list' for main:Object

Answer 1

From pry --help:

-e, --exec A line of code to execute in context before the session starts

So, if your list method is defined on main (if you don’t know, it probably is), then you can do this:

pry -r ./todo.rb -e list

---

Update

Pry doesn’t let you pass in arguments for scripts it loads (or at least it isn’t documented). But all is not lost, you can call pry from your script. Just drop this at wherever you want to inspect:

require 'pry'; binding.pry

This will spawn a pry session that has access to all the local variables and methods.