Qt子类和“对于连接的调用没有匹配函数” [英] Qt Subclassing and "No matching function for call to connect"

问题描述

我试图封装表视图行为，我开始连接表视图头信号到在子类中定义的表视图槽。我可以得到我正在寻找没有亚类的行为，但是失败的目的。当我尝试子类化时，我得到了可怕的没有匹配的函数调用连接。所有组件最终都是QObjects，所以我不认为这是问题。（但是，再次，也许这是问题。）我连接到'hideColumn（）'，但我最终想连接到我自己的插槽（例如'my_sectionClicked（int）'。

I am trying to encapsulate table view behavior and am starting with connecting table view header signals to table view slots defined in the subclass. I can get the behavior I'm looking for without subclassing, but that defeats the purpose. When I do try to subclass, I get the dreaded "No matching function call to connect. All components are ultimately QObjects, so I don't think that's the problem. (But, then again, maybe that IS the problem.) Right now I'm connecting to 'hideColumn()', but I would eventually like to connect to my own slots (such as 'my_sectionClicked(int)'.

是从Jasmin Blanchette和Mark Summerfield的C ++ GUI Programming with Qt 4的源代码绘制的，除了我添加的MyTableView之外。

The code below was drawn from the source for "C++ GUI Programming with Qt 4" by Jasmin Blanchette and Mark Summerfield with the exception of the "MyTableView" addition that I made.

MyTableView。 h

MyTableView.h

#ifndef MYTABLEVIEW_HPP
#define MYTABLEVIEW_HPP

#include <QTableView>

class MyTableView : public QTableView
{
    Q_OBJECT

public:
    explicit MyTableView(QWidget *parent = 0);

public slots:
    void my_sectionClicked(int logicalIndex);

private slots:

public:

private:
    QHeaderView *m_rowHeader;

};

#endif // MYTABLEVIEW_HPP

MyTableView.cpp

MyTableView.cpp

// Qt Includes
#include <QDebug>
#include <QMenu>

// Local Includes
#include "MyTableView.h"

MyTableView::MyTableView(QWidget *parent) : QTableView(parent)
{
    m_rowHeader = horizontalHeader();
    connect(m_rowHeader, SIGNAL(sectionClicked(int)), this, SLOT(hideColumn(int)));
}

void MyTableView::my_sectionClicked(int logicalIndex)
{
    qDebug().nospace() << "Column " << logicalIndex << " selected." << "\n";
}

currencymodel.h

currencymodel.h

#ifndef CURRENCYMODEL_H
#define CURRENCYMODEL_H

#include <QAbstractTableModel>
#include <QMap>

class CurrencyModel : public QAbstractTableModel
{
public:
    CurrencyModel(QObject *parent = 0);

    void setCurrencyMap(const QMap<QString, double> &map);
    int rowCount(const QModelIndex &parent) const;
    int columnCount(const QModelIndex &parent) const;
    QVariant data(const QModelIndex &index, int role) const;
    QVariant headerData(int section, Qt::Orientation orientation,
        int role) const;

private:
    QString currencyAt(int offset) const;

    QMap<QString, double> currencyMap;
};

#endif

currencymodel.cpp

currencymodel.cpp

#include <QtCore>

#include "currencymodel.h"

CurrencyModel::CurrencyModel(QObject *parent)
    : QAbstractTableModel(parent)
{
}

void CurrencyModel::setCurrencyMap(const QMap<QString, double> &map)
{
    currencyMap = map;
    reset(); // Forces views to refresh data 
}

int CurrencyModel::rowCount(const QModelIndex & /* parent */) const
{
    return currencyMap.count();
}

int CurrencyModel::columnCount(const QModelIndex & /* parent */) const
{
    return currencyMap.count();
}

QVariant CurrencyModel::data(const QModelIndex &index, int role) const
{
    if (!index.isValid())
        return QVariant();

    if (role == Qt::TextAlignmentRole)
    {
        return int(Qt::AlignRight | Qt::AlignVCenter);
    }
    else if (role == Qt::DisplayRole)
    {
        QString rowCurrency = currencyAt(index.row());
        QString columnCurrency = currencyAt(index.column());

        if (currencyMap.value(rowCurrency) == 0.0)
            return "####";

        double amount = currencyMap.value(columnCurrency)
                    / currencyMap.value(rowCurrency);

        return QString("%1").arg(amount, 0, 'f', 4);
    }

    return QVariant();
}

QVariant CurrencyModel::headerData(int section,
    Qt::Orientation /* orientation */,
    int role) const
{
    if (role != Qt::DisplayRole)
        return QVariant();
    return currencyAt(section);
}

QString CurrencyModel::currencyAt(int offset) const
{
    return (currencyMap.begin() + offset).key();
}

mainwindow.h

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QtGui>

#include "MyTableView.h"
#include "currencymodel.h"

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow();

protected:

private slots:
    void on_sectionClicked(int locicalIndex);

private:
    QMap<QString, double> currencyMap;
    CurrencyModel currencyModel;
    QTableView tableView;
    QHeaderView *m_rowHeader;
};

#endif

mainwindow.cpp

mainwindow.cpp

#include <iostream>
#include "mainwindow.h"

MainWindow::MainWindow()
{
    currencyMap.insert("AUD", 1.3259);
    currencyMap.insert("CHF", 1.2970);
    currencyMap.insert("CZK", 24.510);
    currencyMap.insert("DKK", 6.2168);
    currencyMap.insert("EUR", 0.8333);
    currencyMap.insert("GBP", 0.5661);
    currencyMap.insert("HKD", 7.7562);
    currencyMap.insert("JPY", 112.92);
    currencyMap.insert("NOK", 6.5200);
    currencyMap.insert("NZD", 1.4697);
    currencyMap.insert("SEK", 7.8180);
    currencyMap.insert("SGD", 1.6901);
    currencyMap.insert("USD", 1.0000);

    currencyModel.setCurrencyMap(currencyMap);

    /*
    THIS WORKS!!!

    m_rowHeader = tableView.horizontalHeader();
    connect(m_rowHeader, SIGNAL(sectionClicked(int)),
        &(tableView), SLOT(hideColumn(int)));
    */

    tableView.setModel(&currencyModel);
    tableView.setAlternatingRowColors(true);

    tableView.setWindowTitle(QObject::tr("Currencies"));
    tableView.show();
}

void MainWindow::on_sectionClicked(int logicalIndex)
{
    qDebug().nospace() << "Column " << logicalIndex << " selected." << "\n";
}

main.cpp

#include "mainwindow.h"

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    MainWindow mainWin;
    return app.exec();
}

我得到的错误是：

g++ -c -pipe -O2 -Wall -W -D_REENTRANT -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_CORE_LIB -DQT_SHARED -I/opt/QtSDK/Desktop/Qt/4.8.1/gcc/mkspecs/default -I. -I/opt/QtSDK/Desktop/Qt/4.8.1/gcc/include/QtCore -I/opt/QtSDK/Desktop/Qt/4.8.1/gcc/include/QtGui -I/opt/QtSDK/Desktop/Qt/4.8.1/gcc/include -I. -I. -o MyTableView.o MyTableView.cpp
MyTableView.cpp: In constructor ‘MyTableView::MyTableView(QWidget*)’:
MyTableView.cpp:11: error: no matching function for call to ‘MyTableView::connect(QHeaderView*&, const char [21], MyTableView* const, const char [17])’
/opt/QtSDK/Desktop/Qt/4.8.1/gcc/include/QtCore/qobject.h:204: note: candidates are: static bool QObject::connect(const QObject*, const char*, const QObject*, const char*, Qt::ConnectionType)
/opt/QtSDK/Desktop/Qt/4.8.1/gcc/include/QtCore/qobject.h:217: note:                 static bool QObject::connect(const QObject*, const QMetaMethod&, const QObject*, const QMetaMethod&, Qt::ConnectionType)
/opt/QtSDK/Desktop/Qt/4.8.1/gcc/include/QtCore/qobject.h:337: note:                 bool QObject::connect(const QObject*, const char*, const char*, Qt::ConnectionType) const
make: *** [MyTableView.o] Error 1

推荐答案

这种问题通常是由于你传递一个已经被向前声明的类，而不是 #include 'd

This kind of problem is usually caused when you're passing a class that has been forward declared, but not #include'd

在你的情况下，你的MyTableView.cpp文件中可能需要一个 #include< QHeaderView> 。

In your case it looks like you probably need a #include <QHeaderView> in your MyTableView.cpp file.

问题是你可以传递指向已经被向前声明的对象的指针，但是编译器不知道你的类最终是从 QObject ，因此在调用 connect（） QObject c $ c>函数。

The issue is that you can pass around pointers to objects that have been forward declared, but the compiler doesn't know that your class is ultimately derived from QObject, so it isn't allowed to use your subclass pointer as a QObject pointer when calling the connect() function.

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