具体实现一个自定义newspaper，reader的信号槽
//!!! Qt5
#include <QObject>
////////// newspaper.h
class Newspaper : public QObject
{
Q_OBJECT
public:
Newspaper(const QString & name) :
m_name(name)
{
}
void send()
{
emit newPaper(m_name);
}
signals:
void newPaper(const QString &name);
private:
QString m_name;
};
////////// reader.h
#include <QObject>
#include <QDebug>
class Reader : public QObject
{
Q_OBJECT
public:
Reader() {}
void receiveNewspaper(const QString & name)
{
qDebug() << "Receives Newspaper: " << name;
}
};
////////// main.cpp
#include <QCoreApplication>
#include "newspaper.h"
#include "reader.h"
int main(int argc, char *argv[])
{
QCoreApplication app(argc, argv);
Newspaper newspaper("Newspaper A");
Reader reader;
QObject::connect(&newspaper, &Newspaper::newPaper,
&reader, &Reader::receiveNewspaper);
newspaper.send();
return app.exec();
}1
//!!! Qt52
3
4
////////// newspaper.h5
class Newspaper : public QObject6
{7
Q_OBJECT8
public:9
Newspaper(const QString & name) :10
m_name(name)11
{12
}13
14
void send()15
{16
emit newPaper(m_name);17
}18
19
signals:20
void newPaper(const QString &name);21
22
private:23
QString m_name;24
};25
26
////////// reader.h27
28
29
30
class Reader : public QObject31
{32
Q_OBJECT33
public:34
Reader() {}35
36
void receiveNewspaper(const QString & name)37
{38
qDebug() << "Receives Newspaper: " << name;39
}40
};41
42
////////// main.cpp43
44
45
46
47
48
int main(int argc, char *argv[])49
{50
QCoreApplication app(argc, argv);51
52
Newspaper newspaper("Newspaper A");53
Reader reader;54
QObject::connect(&newspaper, &Newspaper::newPaper,55
&reader, &Reader::receiveNewspaper);56
newspaper.send();57
58
return app.exec();59
}自定义信号槽需要注意的事项：
- 发送者和接收者都需要是
QObject的子类（当然，槽函数是全局函数、Lambda 表达式等无需接收者的时候除外）； - 使用 signals 标记信号函数，信号是一个函数声明，返回 void，不需要实现函数代码；
- 槽函数是普通的成员函数，作为成员函数，会受到 public、private、protected 的影响；
- 使用 emit 在恰当的位置发送信号；
- 使用
QObject::connect()函数连接信号和槽。
