Meta Object System

The Meta Object System in Qt is responsible for the signal/slot mechanism for communication between objects, runtime type information and the dynamic property system.

元对象系统负责 信号/插槽 机制，用以对象之间的交换，运行时类型信息和动态属性系统。

the QObject class,

the "Q_OBJECT" macro inside the private section of the class declaration and

the Meta Object Compiler (moc).

它包括QObject类型，私有域的Q_OBJECT宏，和元对象编译器。

The moc reads a C++ source file. If it finds one or more class declarations that contain the "Q_OBJECT" macro, it produces another C++ source file which contains the meta object code for this class. This generated source file is either #included into the class' source file or compiled and linked with the class implementation.