title: What is a physical representation of a class?
body: <p>In &quot;Design Patterns - Elements of Reusable Object-Oriented Software&quot; in chapter 1 in Section 1.6 under &quot;Putting Reuse Mechanism to Work&quot; in the &quot;Inheritance versus Composition&quot; part, the author is talking about drawbacks of inheritance:</p>
  <blockquote>
  <p>Second, and generally worse, parent classes often define at least part of their subclasses' <strong>physical representation</strong>.</p>
  </blockquote>
  <p>(emphasis by me)</p>
  <p>What does physical representation mean in this context? I was doing some searching and found <a href="https://stackoverflow.com/questions/1215881/the-difference-between-classes-objects-and-instances">this stackoverflow question</a> where in the answer physical was defined as <em>memory is allocated for the object</em>.</p>
  <p>Does this mean when using inheritance the <em>memory allocation</em> of the object that inherits is partially defined by the object's parent?
  If it does, what does that mean in other words? And why is this a disadvantage?</p>