How to implement an abstract class in Ruby

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Just to chime in late here, I think that there’s no reason to stop somebody from instantiating the abstract class, especially because they can add methods to it on the fly.

Duck-typing languages, like Ruby, use the presence/absence or behavior of methods at runtime to determine whether they should be called or not. Therefore your question, as it applies to an abstract method, makes sense

def get_db_name
   raise 'this method should be overriden and return the db name'
end

and that should be about the end of the story. The only reason to use abstract classes in Java is to insist that certain methods get “filled-in” while others have their behavior in the abstract class. In a duck-typing language, the focus is on methods, not on classes/types, so you should move your worries to that level.

In your question, you’re basically trying to recreate the abstract keyword from Java, which is a code-smell for doing Java in Ruby.

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