如何从插槽中找出哪个信号调用了该插槽? [英] How to find out from the slot which signal has called this slot?
问题描述
我的意思是,如果我有许多不同的信号连接到同一插槽.我看到了这个问题,但无法理解链接答案.能给我一个简单的例子吗?
I mean if I have many different signals which are connected to the same slot. I saw this question but can't understand the link in the answer. Can you give me simple example?
推荐答案
我认为您可以使用此方法: [protected] int QObject :: senderSignalIndex()const
I think you can use this method:
[protected] int QObject::senderSignalIndex() const
根据Qt文档:
返回调用当前正在执行的插槽的信号的元方法索引,该信号是sender()返回的类的成员.如果在信号激活的插槽之外调用,则返回-1.
Returns the meta-method index of the signal that called the currently executing slot, which is a member of the class returned by sender(). If called outside of a slot activated by a signal, -1 is returned.
对于具有默认参数的信号,此函数将始终返回带有所有参数的索引,无论与connect()一起使用哪个参数.例如,信号destroyed(QObject * obj = 0)将具有两个不同的索引(带有和不带有参数),但是此函数将始终返回带有参数的索引.当具有不同参数的信号过载时,这将不适用.
For signals with default parameters, this function will always return the index with all parameters, regardless of which was used with connect(). For example, the signal destroyed(QObject *obj = 0) will have two different indexes (with and without the parameter), but this function will always return the index with a parameter. This does not apply when overloading signals with different parameters.
警告:此功能违反了模块化的面向对象原理.但是,当多个信号连接到单个插槽时,访问信号索引可能会很有用.
Warning: This function violates the object-oriented principle of modularity. However, getting access to the signal index might be useful when many signals are connected to a single slot.
警告:从与该对象的线程不同的线程通过Qt :: DirectConnection调用插槽时,此函数的返回值无效.请勿在此类型的场景.
Warning: The return value of this function is not valid when the slot is called via a Qt::DirectConnection from a thread different from this object's thread. Do not use this function in this type of scenario.
此功能在Qt 4.8中引入.
This function was introduced in Qt 4.8.
这是我为您创建的一个小示例,展示了其工作原理:
Here is a small example that I created for you that demonstrates how it works:
#include <QTimer>
#include <QMetaObject>
#include <QMetaMethod>
#include <QCoreApplication>
#include <QDebug>
#include <QObject>
class Foo : public QObject
{
Q_OBJECT
public slots:
void mySlot() {
QMetaMethod metaMethod = sender()->metaObject()->method(senderSignalIndex());
qDebug() << metaMethod.name();
qDebug() << metaMethod.methodSignature();
qApp->quit();
}
};
#include "main.moc"
int main(int argc, char **argv)
{
QCoreApplication coreApplication(argc, argv);
QTimer timer;
Foo foo;
QObject::connect(&timer, &QTimer::timeout, &foo, &Foo::mySlot);
timer.setSingleShot(true);
timer.start(1000);
return coreApplication.exec();
}
main.pro
TEMPLATE = app
TARGET = main
QT = core
CONFIG += c++11
SOURCES += main.cpp
构建并运行
qmake && make && ./main
输出
"timeout"
"timeout()"
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