Vertical vs. Horizontal Decomposition of Responsibility

Objects responsible for too many things are a problem. Because their complexity is high, they are difficult to maintain and extend. Decomposition of responsibility is what we do in order to break these overly complex objects into smaller ones. I see two types of this refactoring operation: vertical and horizontal. And I believe the former is better than the latter.

Once Upon a Time in America (1984) by Sergio Leone

Let's say this is our code (it is Ruby):

class Log def initialize(path) @...