Why does an abstract class have a vtable?
<p>Regarding <a href="https://stackoverflow.com/questions/2592438/does-an-abstact-classes-have-a-vtable" title="this">this</a> post:</p>

<blockquote>
  <p>For implementations that use vtable, the answer is: Yes, usually. You
  might think that vtable isn't required for abstract classes because
  the derived class will have its own vtable, <strong>but it is needed during</strong>
  <strong>construction: While the base class is being constructed, it sets the</strong>
  <strong>vtable pointer to its own vtable. Later when the derived class</strong>
  <strong>constructor is entered, it will use its own vtable instead.</strong></p>
</blockquote>

<p>I'm assuming the answer is correct, but I don't quite get it. Why is the vtable needed exactly for construction?</p>