flex notes 之：对getter函数的数据绑定

天天忙于实际项目的结果之一，就是来来回回反反复复测代码，就是不愿意停下来查原理。

这会儿实在不想test了，查了查把数据绑定到getter function上为何不更新。flex帮助文档结果如下：

Using read-only properties as the source for data binding

You can use a read-only property defined by a getter method, which means no setter method, as the source for a data-binding expression. Flex performs the data binding once when the application starts.

原来只在程序初始化时执行一次绑定，所以在必要时还得用事件推一推。