[android2]

"To work correctly, classes with virtual methods must also have virtual destructors."

Not a good way to start the article... I immediately question the author's credibility following this statement.

[tomjen3]

Why? If they don't it is going to mess up the destruction sequence if they are ever stored and then released polymorphically, such as from a collection of pointers to classes.

What he is saying is standard C++ knowledge.

[Rexxar]

You can also use a protected non-virtual destructor in the base class to avoid to mess up the destruction sequence. But what he says is indeed the most common case.

[_stephan]

Sometimes an alternative is to make the destructor in the base class protected.