Writing ruby code that only executes in development mode

[tweetmeme]
Our application does a lot of parsing of tree structures in development mode which aids our application developers in creating squeeky-clean code. However, in production we don’t really want and don’t need the overhead of all these additional recursive tree-parsing methods, but we also don’t want to change the application code.

The answer is to leave the application code making calls to the platform, but adapting the methods in the platform to only execute the method bodies in development mode.

We have a module that is mixed in where appropriate:

module DefineInDevelopment

  # Defines a method used to define other methods that are only available in development mode
  if ENV['RAILS_ENV'] == "development"
    def define_in_development
      yield
    end
  else
    def define_in_development
    end
  end

end

Then in any method where we only want the processing overhead in development, we wrap the method’s body in a define_in_development method call passing a block:

include DefineInDevelopment
def my_expensive_method_for_development(arg1, arg2) do
  define_in_development do
    # really expensive code
  end
end

Simple, but incredibly effective! Exploring this also identified a performance gotcha which I discuss in my next blog entry.