CODEWITHSUNDEEP
rubyscopemetaprogrammingvisibility
knub
knub

Reputation: 4032

Ruby print current visibility

So, with all the metaprogramming stuff in ruby (using 1.9.3), I guess there is a method which returns the current visibility. Lets assume it is called visibility.

class Foo
  puts visibility
  # => "public"

  private
  puts visibility
  # => "private"
end

So, whats visibility - how can I get the current visibility the ruby interpreter uses when he finds new methods definitions?

Upvotes: 2

Views: 255

Answers (2)

sylvain.joyeux
sylvain.joyeux

Reputation: 1699

AFAIK, there isn't a ready to use method. You could implement one, however, with something along the lines of (untested)

class Class
  def visibility
    define_method(:__visibility_discovery__) { }
    visibility =
      if protected_method_defined? :__visibility_discovery__
        "protected"
      elsif private_method_defined? :__visibility_discovery__
        "private"
      else
        "public"
      end
    remove_method :__visibility_discovery__
  end
end

Upvotes: 1

Anthony DeSimone
Anthony DeSimone

Reputation: 2034

In Ruby, you have three different levels of visibility for instance methods.

Methods default to public, which is what you are probably used to. You always have access to this method if you have access to the object.

private and protected are similar. They can only be accessed by the class and subclasses. The difference is that public methods cannot be called with an explicit receiver. What that means is you cannot call another method's private function from another instance of the same class, while protected can.

So if you need methods to be available outside of your class, stick to the default visibility of public. If your method needs to be accessed by any instance of that class, such as some custom comparison logic, use protected. And if your method is anything that should not be visible outside an instance of that class, use private.

To actually answer your question, visbility is a method that returns the current state of visibility - whether it is public, private, or protected.

Upvotes: 0

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