When booking a hotel or a flight for your next trip you could do it the old way: surfing a lot of websites looking for cheap and relevant offerings. Or you could apply "Inversion of Control": specify your wishes regarding travel and accomodation and then wait for a lot of hotels and airlines to send offerings for you to choose from. Hotwire is one example of that kind of service.


When surfing the net, a lot of websites "push" commercials onto your screen earning money to the people running those websites. Wouldn't it be nice if you instead could "pull" selected commercials and thereby provide funding to your favorite charity? AidOnline is one (Danish) example of that kind of service.

As a programmer it seems to me that these two examples of "Inversion of Control" are structurally similar to the popular unit testing technique called "Dependency Injection".

Can you come up with other interesting examples of "Inversion of Control"?

By Lars Thorup