QT qobject_cast用法

文档：

T qobject_cast(QObject * object)
Returns the given object cast to type T if the object is of type T (or of a subclass); otherwise returns 0. If object is 0 then it will also return 0.

The class T must inherit (directly or indirectly) QObject and be declared with the Q_OBJECT macro.

A class is considered to inherit itself.

Example:

QObject *obj = new QTimer;          // QTimer inherits QObject

QTimer *timer = qobject_cast(obj);
// timer == (QObject *)obj

QAbstractButton *button = qobject_cast(obj);
// button == 0
The qobject_cast() function behaves similarly to the standard C++ dynamic_cast(), with the advantages that it doesn't require RTTI support and it works across dynamic library boundaries.

qobject_cast() can also be used in conjunction with interfaces; see the Plug & Paint example for details.

翻译：

T qobject_cast（qobject*o