QT qScriptConnect is not working

Question

QScriptEngine eng;
QScriptEngineDebugger debugger;
debugger.attachTo(&eng);
QScriptValue consoleObj =  eng.newQObject(this);
eng.globalObject().setProperty("asd", consoleObj);
QScriptValue handler= eng.evaluate("(function(text) { asd.log('text was changed to '+text); })");
QLineEdit *edit = new QLineEdit(this);
qScriptConnect(edit, SIGNAL(textChanged(QString)), QScriptValue(), handler);
edit->show();

qScriptConnect(edit, SIGNAL(textChanged(QString)), QScriptValue(), handler)不起作用，但是当我使用handler.call(QScriptValue(),args)时它运行良好;

QScriptValueList args;
args << 3;
handler.call(QScriptValue(),args);

主窗口.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
Q_INVOKABLE void log(QString msg);
~MainWindow();
private slots:
private:
Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H

主窗口.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include<qscriptengine.h>
#include<qscriptenginedebugger.h>
#include<qlineedit.h>
#include<qdebug.h>
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
QScriptEngine eng;
QScriptEngineDebugger debugger;
debugger.attachTo(&eng);
QScriptValue consoleObj =  eng.newQObject(this);
eng.globalObject().setProperty("asd", consoleObj);
QScriptValue handler= eng.evaluate("(function(text) { asd.log('text was changed to '+text); })");
QLineEdit *edit = new QLineEdit(this);
qDebug()<<qScriptConnect(edit, SIGNAL(textChanged(QString)), QScriptValue(), handler);
edit->show();
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::log(QString msg)
{
qDebug() << "jsConsole: "<< msg;
}

Answer 1

在方法中创建的变量未在堆中创建的变量在完成方法执行时将被删除，在您的情况下，QScriptEngine是在构造函数中创建的，原因将其消除，并且所有脚本都依赖于它。解决方案很简单，使类的QScriptEngine成员：

主窗口.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QScriptEngine>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
Q_INVOKABLE void log(const QString & text);
private:
Ui::MainWindow *ui;
QScriptEngine eng; // member
};
#endif // MAINWINDOW_H

主窗口.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QLineEdit>
#include <QScriptEngine>
#include <QScriptEngineDebugger>
#include <QDebug>
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
QScriptEngineDebugger debugger;
debugger.attachTo(&eng);
QScriptValue consoleObj =  eng.newQObject(this);
eng.globalObject().setProperty("asd", consoleObj);
QScriptValue handler= eng.evaluate("(function(text) { asd.log('text was changed to '+text); })");
QLineEdit *edit = new QLineEdit(this);
qScriptConnect(edit, SIGNAL(textChanged(QString)), QScriptValue(), handler);
edit->show();
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::log(const QString &text)
{
qDebug()<< text;
}