An article called Why Extends Is Evil will surely list one or two. Holub exaggerates a bit, but has some solid examples of the perils of inheritance.
A good question is never answered. It is not a bolt to be tightened into place but a seed to be planted and to bear more seed toward the hope of greening the landscape of the idea. John Ciardi
With a little knowledge, a cast iron skillet is non-stick and lasts a lifetime.