I’ve recently been reading Refactoring: Ruby Edition by Jay Fields, Martin Fowler, and Shane Harvie. All in all it’s a fantastic book and I’ve learned a lot from it, I’d definitely recommend it. However, there was one section that pretty much made me do this:

Nope Octopus

That section was on Dynamic Method Definitions. Normally in Ruby, if you’d like to define a method you do it between a def and an end. However, there may be a situation in which you have many methods that all have a similar structure and it gets repetitive. For example, lets say we’ve got a kid that has some chores to do.

  def wash_dog

  def wash_dishes

  def wash_car

Obviously this is a pretty contrived example, but stay with me. If we wanted to dynamically define these methods instead of doing each one individually we could instead do:

["dog", "dishes", "car"].each do |method|
  define_method "wash_#{method}" do

There are a lot of benefits to this, it obviously reduces duplication in the code and as a result of that can also reduce the possibility for errors when compared to defining the methods individually.

However, to me the benefits are not worth the huge downside of reducing readability and easy code navigation. Oftentimes when going throw a codebase we use some go-to tricks for finding where a method is defined when we need to know more about it. If I went into a codebase and saw the wash_car method and wanted to find it’s definition I would immediately search for def wash_car. When it didn’t come up I’d think, maybe it’s an instance variable with an attr_reader and search for that. Nope? Maybe it’s delegated from another object. Nope? Maybe it’s an alias. Nope? WHERE THE F*CK is it defined?

I personally will always favor readibility over brevity. If there were 100 of these small chore methods then at that point it may be worth the trade-off, but with only a couple of them I don’t think Dynamic Method Definiton is worth it. Many people would disagree with me, it’s kind of like the argument of using a ternary vs an if/else for a short conditional. Some people think it’s awesome, some people think it’s Ruby Golf. Either way, I’m sticking by my PSA. Friends Don’t Let Friends Use Dynamic Method Definition.