Is there a more succinct way to write this Ruby function?

Question

Just for fun, I want to try to write this Ruby function more succinctly. I imagine it can be done, I'm just not knowledgeable enough with Ruby yet to know how. Any suggestions?

  def tags
    return ['Cancelled'] if cancelled?
    tags = []
    tags << 'Filled' if filled?
    tags << 'In Progress' if in_progress?
    tags
  end 

Answer 1

def tags
  if cancelled? then ["Cancelled"]
  else [*("Filled" if filled?), *("In Progress" if in_progress?)]
  end
end

If you design your code so that filled? and in_progress? be false whenever cancelled? is true, then the logic will be much prettier:

def tags
  [
    *("Cancelled" if cancelled?),
    *("Filled" if filled?),
    *("In Progress" if in_progress?),
  ]
end

Answer 2

Functional approach:

def tags
  if cancelled?
    ["Cancelled"]
  else
    [("Filled" if filled?), ("In Progress" if in_progress?)].compact
  end
end

Ideas behind the snippet:

• Don't perform imperative side-effects on arrays (unless performance is a problem, not the case here).
• Use the pattern: array of "nilable" expressions + compact to build arrays with conditional elements.
• Minimize the use of inline conditional statements, they make a function harder to understand. They are ok as guards (early exit of functions), but not here. Note that I do use inline ifs, but they are expressions, not statements; more orthodox -but also more verbose- would be (filled? ? "Filled" : nil).

Answer 3

Not exactly the same, but here's another idea:

def tags
  [ :cancelled?, :filled?, :in_progress? ].map do |m|
    m.to_s if send( m )
  end.compact
end

Answer 4

def tags
  [].tap do |a|
    cancelled? ? a << "Cancelled" : (a << "Filled" if filled?; a << "In Progress" if in_progress?)
  end
end