Make tap{} return anything

If you are a fan of tap method you probably used it to make compact assignments like that:

def sources
  @sources ||= [].tap do |s|
    s << "source1"
    s << "source2"
  end
end

or to make nice looking one-liners of chained methods operating on and returning the original object:

[1,2,3,4,5].tap{ |a| a.delete(2) }.reverse

Besides that tap may be helpful in creating flow control statements that return anything you want instead of an object that you tapped into. That allows you to create one-liners that generate new objects based on the original one:

[1,2,3,4].tap{ |a| break a.count > 1 ? [a.first] : a }

The magic keyword here is the break. If you pass some object to it then the result of calling a tap will be that object.