Qt“私有时隙：这是什么？ [英] Qt "private slots:" what is this?

问题描述

我明白如何使用它，但它的语法困扰我。什么是private slots：？？

我从来没有见过private关键字和之前的类定义。这里是否有一些奇特的C ++魔术？

并且这里的例子：

  #include< QObject> 
 
 class Counter：public QObject 
 {
 Q_OBJECT 
 
 public：
 Counter（）{m_value = 0; } 
 
 int value（）const {return m_value; } 
 
 public slots：
 void setValue（int value）; 
 
 ... 
  

解决方案

插槽是C ++的Qt特定扩展。它只有在通过Qt的预处理器Meta-Object Compiler（moc）发送代码之后才编译。有关文档，请参见 http://doc.qt.io/qt-5/moc.html 。 / p>

编辑：正如Frank指出的，只有链接才需要moc。额外的关键字使用标准预处理程序#defined。

I understand how to use it, but the syntax of it bothers me. What is "private slots:" doing?

I have never seen something between the private keyword and the : in a class definition before. Is there some fancy C++ magic going on here?

And example here:

 #include <QObject>

 class Counter : public QObject
 {
     Q_OBJECT

 public:
     Counter() { m_value = 0; }

     int value() const { return m_value; }

 public slots:
     void setValue(int value);

 ...

解决方案

Slots are a Qt-specific extension of C++. It only compiles after sending the code through Qt's preprocessor, the Meta-Object Compiler (moc). See http://doc.qt.io/qt-5/moc.html for documentation.

Edit: As Frank points out, moc is only required for linking. The extra keywords are #defined away with the standard preprocessor.

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