🚀 go-pugleaf

Regards ~virtual:

Also note, under today's system, where a derived class cannot explicitly
declare a method ~virtual, the possibility exists for a base class
programmer to "hijack" a private derived class method by declaring
it public virtual in the base class.  For example, when modifying
a base class, the base class programmer might accidentally choose a virtual 
function name used privately non-virtually in a derived class.  
The effect would be that what was intended to be a private non-virtual 
method in the derived class is accidentally promoted, without warning, 
to become one flavor of a public virtual method of the base class.

If the derived class programmer could explicitly mark private non-virtual
methods with ~virtual, then attempts to make such virtual in the base 
class would cause an error.  I claim this is how it should be.  Base
classes should be able to protect and defend methods declared in the
base class.  Derived classes should be able to protect and defend methods
declared in the derived class.  If the two classes refuse to agree,
a compile-time error should result.