Quick Tip: More Readable Conditionals in Ruby

When Code Climate and Tammer Saleh from Thunderbolt Labs teamed up to offer free code reviews at RubyConf, I seized the opportunity to get feedback on my first Ruby gem – gnip-rule). A number of refactorings came out of that session, but one I found most interesting was an approach to making conditionals more maintainable in languages like Ruby and CoffeeScript.

They say that the use of conditionals in Ruby is a code smell. Decisions about how your team approaches conditionals should be discussed then outlined in your project styleguide.

This is the refactoring I’m talking about – I have a bunch of different checks according to Gnip’s PowerTrack API constraints to ensure that a PowerTrack rule follows the constraints.

module GnipRule
  class Rule
    def valid?
      # So many ORs
      if contains_stop_word? || too_long? || contains_negated_or? || too_many_positive_terms? || contains_empty_source?
        return false
      end
      true
    end

    # def contains_stop_word?..end etc.
  end
end

…And here is the same method, refactored. We turned each condition into an early return if the conditional expression is true:

module GnipRule
  class Rule
    def valid?
      return false if too_long?
      return false if too_many_positive_terms?
      return false if contains_stop_word?
      return false if contains_empty_source?
      return false if contains_negated_or?
      return true
    end
  end
end

Some might cringe at seeing so many return statements, but I argue that it’s more maintainable this way because it’s obvious to the reader what is being checked. If another check is added, it doesn’t hang off a long chain of ||s (or use a bunch of ugly \s to break lines).

Not only is this useful in Ruby, but CoffeeScript as well. Example:

stringify = (obj) ->
  return 'undefined' if obj is undefined
  return 'null' if obj is null
  return obj if (typeof obj is 'string' or Number.isFinite(obj))
  return "[#{obj.join(', ')}]" if obj instanceof Array
  return Object.prototype.toString.call(obj)

Thank you again, Tammer, for your very helpful advice.

What do you think of this formatting?

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