Not a very convincing example. A component provides a callback, and then the callback ends up using the same DB access mechanism that the component is using? Or

Not a very convincing example. A component provides a callback, and then the callback ends up using the same DB access mechanism that the component is using? Or the same lock? I mean, is it providing a callback to itself? Layering the code, or isolating the component from those who subscribe these unpredictable callbacks seem kind of obvious to me, and would prevent all of this. The author is right, though - there is something to take away from this, but I think it's simply the importance of clean separation of concerns. Or, the importance of good factoring, if I'm using the word correctly? Other than that, we're entering the realm of the eternal programmers' dream: programs that write themselves...