There are a lot of scenarios where you might want to share contextual information between the view that is hosting a region and a view that is inside a region. For example, a master detail–like view shows a business entity and exposes a region to show additional detail information for that business entity. The Prism Library uses a concept named RegionContext to share an object between the host of the region and any views that are loaded inside the region, as shown in the following illustration.
大意就是,在父视图中,添加一个Region,用来显示扩展信息,并且指定这个Region的DataContext(但是官方说This approach is somewhat similar to the DataContext, but it does not rely on it.),也就是说,仅仅是像而已!也就是说,不不用再为这个即将加载进来的视图,单独设置DataContext,任何一个加载进来的视图都共享这个RegionContext。