Question

Here’s what I’d like to do:

class Directory
  def doSomething
  end

  def subs
    # => an array of Directory objects
  end

  def recursively (method)
    self.subs.each do |sub|
      sub.method
      sub.recursively method
    end
  end
end

cd = Directory.new

cd.recursively 'doSomething'
# ...and extra points if theres a way to:
cd.recursively.doSomething

To put this into perspective I’m creating a small script that will make changes to files in a Directory as well as all its sub-directories. These sub-directories will just be extended Directory objects.

So is there a way to pass a method as a parameter of another method?

Answer 1

You could use Object#send, where method is a string or symbol representing the method name, as in your first example. Just change your #recursively to this:

def recursively(method)
  subs.each do |sub|
    sub.send method
    sub.recursively method
  end
end

UPDATE

For your “extra points” question, and picking up on megas’ answer, here’s a stab at an Enumerator-based approach. Drop this into your Directory:

def recursively
  Enumerator.new do |y|
    subs.each do |sub|
      y.yield sub
      sub.recursively.each do |e|
        y.yield e
      end
    end
  end
end

And call it like this:

cd.recursively.each { |d| d.doSomething }