Qt 的良好封装机制使得 Qt 的模块化程度非常高，可重用性较好，对于用户开发来说是非常 方便的。 Qt 提供了一种称为 signals/slots 的安全类型来替代 callback，这使得各个元件之间的协同工作变得十分简单。-Qt' s good encapsulation mechanism makes very high degree of Qt modular, reusable better, it is very convenient for users to develop. Qt provides the type of security called the signals/slots to replace the callback, which makes collaborative work between the various components is very simple.