title: Kotlin parent logic to run after child's constructor
body: <p>I got the following classes:</p>
  <pre><code>class B() : A {
      override val p1: String = ...
      override fun p2() : String { ... }
  }
  
  abstract class A() {
      abstract val p1: String
      abstract fun p2() : String
      fun p3() : String = p1.plus(&quot;-&quot;).plus(p2())
      init {
         var p4 = p3()
      }
  
  }
  </code></pre>
  <p>I want <code>p4</code> to be set at declaration. the issue is that when A() constructor is called <code>p1</code> &amp; <code>p2()</code> are not set yet, so <code>p3()</code> contains nulls. is there a way to solve it? like to run some logic after both constructors are called?</p>