instantaneous feedback of the console with the structure and organization of Ruby objects Blend the As Rails developers, it is imperative that we be comfortable and productive in the console. The console is where we have the shortest feedback cycles, making it perfect for learning and tinkering. The console is useful in debugging code, local data, and trying out new ideas and implementations. Rails manipulating However, once we emerge from the weeds and start working on more involved problems, the console’s blade begins to lose its sharpness. Fortunately, we can blend the instantaneous feedback of the console with the structure and organization of Ruby objects/methods by using a scratchpad file. A scratchpad is a file that is loaded automatically onto all Rails console sessions. Making a scratchpad file with Pry I recommend using Pry ( ) as a console. Pry automatically loads a file named in the app’s root (and also in ) whenever a console is launched ( or ). We can use that file to load our scratchpad. pry-rails .pryrc ~/.pryrc rails console binding.pry First, create a scratch.rb file in the Rails root directory ( ). Then load the scratchpad file in the : touch scratch.rb scratch.rb .pryrc Here is a basic scratch file with an example: module Scratch def scratch! load __FILE__ end def my_scratch_method puts "my_scratch_method was called" end def my_user User.find_by(email: "my@email.com") end end include Scratch The Scratch module loads in and is included into the Pry console session, meaning that all methods defined within it are now available in the console. scratch.rb Note that I have added a method to the module which reloads the file to the latest saved version without having to reload the entire console. This allows you to change code in the module and receive feedback in real time by chaining : #scratch! Scratch #scratch! scratch!; my_scratch_method Another handy use for the scratch file is to add commonly used helper methods that don’t belong in the source code. For example, I keep a progress bar setup handy: require 'ruby-progressbar' module Scratch def each_with_progress_bar(scope, &block) progress_bar = ProgressBar.create progress = progress_bar(scope.count)scope.find_each do |item| block.call(item).tap do progress.increment end end end ... end module Scratch There are a bunch of interesting use cases for having a scratchpad file available in the console. If you have an interesting one, drop me a comment. I’d love to learn how others use scratchpads. I learned this trick from my co-worker, friend, and walking vim encyclopedia Scott Pierce ( ). @ddrscott
