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Object-Oriented Programming II
Private! Keep Out!

Perfect! But not all our Ruby methods should be public.

Just as we use public to announce our public methods, we use private to specify our private ones:

class ClassName # Some class stuff public # Public methods go here def public_method; end private # Private methods go here def private_method; end end

private methods are just that: they’re private to the object where they are defined. This means you can only call these methods from other code inside the object. Another way to say this is that the method cannot be called with an explicit receiver. You’ve been using receivers all along—these are the objects on which methods are called! Whenever you call object.method, object is the receiver of the method.

In order to access private information, we have to create public methods that know how to get it. This separates the private implementation from the public interface, and we’ll go over this in more detail in the next two exercises.

Instructions

1.

Add a private method called id to Dog. The id method should create an @id_number instance variable and set it equal to 12345.

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