The Bridge pattern
The Bridge pattern is a structural design pattern that lets you split a large class or set of closely related classes into two separate hierarchies: abstraction and implementation. Kitty and Phoebe set up a Kickstarter page to promote Bumble Bikes and gauge the interest on the market. Backers can preview and pre-order the Palo Duro Canyon Ranger, Bumble Bike’s flagship mountain bike design. The project has been well received, but the Kickstarter backers are complaining about the lack of color choices on the bikes. In the original design, the girls purposefully limited the color choices because they were using inheritance for almost everything. The problem with using inheritance is becoming a clear theme: it can lead to a run-away proliferation of classes, as seen in Figure 4.13. Can you imagine supporting 20 colors per bicycle model, and expanding to 20 models of bicycles? That’s a lot of subclasses!
Figure 4.13: Class proliferation...
