title: Unions as Base Class
body: <p>The standard defines that Unions cannot be used as Base class, but is there any specific reasoning for this? As far as I understand Unions can have constructors, destructors, also member variables, and methods to operate on those varibales. In short a Union can encapsulate a datatype and state which might be accessed through member functions. Thus it in most common terms qualifies for being a class and if it can act as a class then why is it restricted from acting as a base class? </p>
  
  <p>Edit: Though the answers try to explain the reasoning I still do not understand how Union as a Derived class is worst than when Union as just a class. So in hope of getting more concrete answer and reasoning I will push this one for a bounty. No offence to the already posted answers, Thanks for those! </p>