QT meta object qmetaobject indexofslot and other functions to obtain class methods attention

• indexOfSlot Return from QObject Index of slot function in derived class , If there is a specified slot function , Then return to non -1 Value , If it doesn't exist , Then return to -1.

• indexOfMethod Return from QObject Index of any function of derived class , If there is a specified function , Then return to non -1 Value , If it doesn't exist , Then return to -1.

• indexOfSignal Return from QObject Index of any signal of derived class , If there is a specified signal , Then return to non -1 Value , If it doesn't exist , Then return to -1.

The following for QtWidgetsApplication2.h：

#pragma once

#include <QtWidgets/QWidget>
#include "ui_QtWidgetsApplication2.h"
#include"test.h"
class QtWidgetsApplication2 : public QWidget
{
    Q_OBJECT
signals:
    void setValueSignal(int);
    void testSignal(int&);
public slots:
    int setMyAge(int&);
    int setValue(int nValue);
    int setValue(int* pValue);
    void setColor(const QColor& clr);
    void setTest(const CTest& test);
public:
    QtWidgetsApplication2(QWidget *parent = Q_NULLPTR);
private:
    Ui::QtWidgetsApplication2Class ui;
  
};

QtWidgetsApplication2.cpp Document code omitted . The following for test.h

#pragma once
class CTest
{
public:
	CTest() {};
	~CTest() {};
};

The following for main：

#include "QtWidgetsApplication2.h"
#include <QtWidgets/QApplication>
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QtWidgetsApplication2 w;
   
   auto nIndex1 = w.metaObject()->indexOfSlot("setValue(int)");
   auto nIndex2 = w.metaObject()->indexOfSlot("setMyAge(int&)");
   auto nIndex3 = w.metaObject()->indexOfSlot("setValue(int*)");
   auto nIndex4 = w.metaObject()->indexOfSlot("setColor(QColor)");
   auto nIndex5 = w.metaObject()->indexOfSlot("setTest(CTest)");
  
   qDebug() << "nIndex1:" << nIndex1 << "nIndex2:" << nIndex2
       << "nIndex3:" << nIndex3 << "nIndex4:" << nIndex4
       << "nIndex5:" << nIndex5 << "\r\n";

   auto nIndex6 = w.metaObject()->indexOfSlot("int setValue(int)");
   auto nIndex7 = w.metaObject()->indexOfSlot(" setValue(int)");
   auto nIndex8 = w.metaObject()->indexOfSlot("setValue(int )");
   auto nIndex9 = w.metaObject()->indexOfSlot("setValue(int value)");

   qDebug() << "nIndex6:" << nIndex6 << "nIndex7:" << nIndex7
       << "nIndex8:" << nIndex8 << "nIndex9:" << nIndex9 << "\r\n";

   auto nIndex10 = w.metaObject()->indexOfSlot("setColor(const QColor)");
   auto nIndex11 = w.metaObject()->indexOfSlot("setColor(QColor&)");
   auto nIndex12 = w.metaObject()->indexOfSlot("setColor(const QColor&)");

   auto nIndex13 = w.metaObject()->indexOfMethod("setValue(int)");
   auto nIndex14 = w.metaObject()->indexOfMethod("dansir(int)");

   qDebug() << "nIndex10:" << nIndex10 << "nIndex11:" << nIndex11
       << "nIndex12:" << nIndex12 << "nIndex13:" << nIndex13
       << "nIndex14:" << nIndex14 << "\r\n";

   auto nIndex15 = w.metaObject()->indexOfSignal("setValueSignal(int)");
   auto nIndex16 = w.metaObject()->indexOfSignal("setValueSignal(int )");
   auto nIndex17 = w.metaObject()->indexOfSignal("testSignal(int&)");

   qDebug() << "nIndex15:" << nIndex15 << "nIndex16:" << nIndex16
       << "nIndex17:" << nIndex17 << "\r\n";

    w.show();

    return a.exec();
}

The input results on my machine are as follows ：

From the above input results , Summarized below ：

• The parameters of these functions pass in the function or signal to be searched , It does not include the return value of function or signal , Otherwise it will return to -1, Such as ： The first 18 Line .
• The parameters of these functions pass in the function or signal to be searched , And there must be no space between the function name and double quotation marks , Otherwise it will return to -1, Such as ： The first 19 Line .
• The parameters of these functions pass in the function or signal to be searched , If there is a parameter type , Then there must be no space between the parameter type and the parentheses , Such as ： The first 20 Line .
• The parameters of these functions pass in the function or signal to be searched , You can take parameter types , But no specific parameter name , Such as ： The first 21 Line .
• The parameters of these functions pass in the function or signal to be searched , If the parameter is a reference and the parameter type is not int、double Basic data types such as , Then remove the reference symbol , Such as ：setColor(QColor&) Returns the -1, Need to put setColor(QColor&) Change it to setColor(QColor), If the parameter has const, Will return to -1, Need to put const Get rid of , namely setColor(const QColor&) Should be changed to setColor(QColor).

Sum up ： These three indexOf The parameters of the first function are ：

• Function or signal name to search .
• Function or signal names cannot have return values .
• If the function or signal name has parameters , Only parameter types can be taken , No specific parameter name .
• If the function or signal name has parameters , There cannot be spaces between parameter types and braces .
• There must be no space between the function or signal name and the double quotation marks .
• Non basic data type const Or the quotation should be removed .