带有自定义类的 QtScript instanceof 会引发原型相关的错误

Question

我有一个 Qt 项目，它使用 QtScript 模块使我的应用程序的某些组件可编写脚本。

在多次尝试使现有的类直接在 QtScript 中使用之后，我选择使用继承 QObject 和 QScriptable 的包装类（主要是因为我有一些非 qobject 派生类，它们被其他继承或不继承 QObject 的类继承，并且它是因此我不可能统一对待我所有的课程）。

我现在尝试使用基于原型的继承。

我必须创建具有相应包装器 Wrapper_Drawable 和 Wrapper_MeshDrawable 的 Drawable 和 MeshDrawable 类。 MeshDrawable继承Drawable，Wrapper_MeshDrawable继承Wrapper_Drawable。

我让脚本引擎知道这两个类（m_scriptEngine）：

Wrapper_Drawable* wrapper_drawable = new Wrapper_Drawable();
QScriptValue wrapper_drawable_obj = m_scriptEngine->newQObject(wrapper_drawable);
m_scriptEngine->setDefaultPrototype(qMetaTypeId<Wrapper_Drawable*>(),
                                    wrapper_drawable_obj);

Wrapper_MeshDrawable* wrapper_meshDrawable = new Wrapper_MeshDrawable();
QScriptValue wrapper_meshDrawable_obj = m_scriptEngine->newQObject(wrapper_meshDrawable);
m_scriptEngine->setDefaultPrototype(qMetaTypeId<Wrapper_MeshDrawable*>(),
                                    wrapper_meshDrawable_obj);

如果我没记错的话，文档说脚本引擎会将 Wrapper_Drawable 的原型应用于类型 Wrapper_MeshDrawable 因为它们在 C++ 中具有继承关系。

我有一个方法 Wrapper_Drawable::drawables() ，它返回 Wrapper_Drawable 的所有子级（实际上是包装在 Wrapper_Drawable 中的 Drawable 的子级） >）。由于 Drawable 是一个抽象类，因此所有子级实际上都是 MeshDrawable。

因为我希望用户“相信”他使用 Drawable 而不是 Wrapper_Drawable，所以我声明：

m_scriptEngine->globalObject().setProperty("Drawable", wrapper_drawable_obj);

其中wrapper_drawable_obj 已在上面声明。

---

我想测试引擎是否能够识别 Wrapper_MeshDrawable，即使它们是在 Wrapper_Drawable 数组中声明的。

curChildren = myDrawable.drawables()[0];
print(curChildren instanceof Drawable);

遗憾的是，instanceof 抛出了这个错误：

TypeError: instanceof called on an object with an invalid prototype property.

如果我尝试执行 curChildren instanceof Number 它会返回 false，所以我猜问题与 Wrapper_Drawable 有关，但我无法弄清楚它到底是什么。

预先感谢您的善意帮助。

编辑>我添加了ScriptManager（处理脚本引擎并声明各种类型）、Wrapper_Drawable（只有一些方法，否则我无法发布此消息）和Wrapper_MeshDrawable的代码。

我还仔细检查了 Wrapper_Drawable 对象上的 instanceof，对于 Number 返回 false，对于 Object 返回 true，并使用 Drawable 抛出上述错误（与名称不同，这是一个 Wrapper_Drawable 对象） ）。

因此，有 Wrapper_Drawable 类的代码：

#ifndef WRAPPER_DRAWABLE_H
#define WRAPPER_DRAWABLE_H

#include <QObject>
#include <QScriptable>

#include "../drawable.h"

class Wrapper_Drawable : public QObject, public QScriptable
{
    Q_OBJECT
public:
    explicit Wrapper_Drawable(Drawable* drawable = 0, QObject *parent = 0);

    virtual Drawable* drawable() const;
signals:

public slots:
    QScriptValue visible() const;

    virtual QScriptValue loadData();

    QScriptValue rotate();
    QScriptValue translate();
    QScriptValue scale();

    QScriptValue modelMatrix() const;
    QScriptValue completeModelMatrix() const;

    QScriptValue name() const;
    QScriptValue setName();

    QScriptValue shaderProgramName() const;
    QScriptValue setShaderProgramName();

    QScriptValue row() const;

        QScriptValue childCount() const;

    QScriptValue child() const;
    QScriptValue appendChild();
    QScriptValue insertChildren();
    QScriptValue insertChild();
    QScriptValue removeChildren();

    QScriptValue children() const;
    QScriptValue visibleChildren() const;

    QScriptValue parent() const;
    QScriptValue setParent();

protected:
    Drawable* m_drawable;
};

Q_DECLARE_METATYPE(QList<Wrapper_Drawable*>)
Q_DECLARE_METATYPE(Wrapper_Drawable*)

#endif // WRAPPER_DRAWABLE_H

CPP:

#include "wrapper_drawable.h"

Wrapper_Drawable::Wrapper_Drawable(Drawable *drawable, QObject *parent) :
    QObject(parent), m_drawable(drawable)
{
}

Drawable* Wrapper_Drawable::drawable() const {
    return m_drawable;
}

QScriptValue Wrapper_Drawable::removeChildren() {
    Wrapper_Drawable* wrapper_drawable = qscriptvalue_cast<Wrapper_Drawable*>(context()->thisObject());

    if(!wrapper_drawable)
        return context()->throwError(QScriptContext::TypeError, "Drawable.insertChildren: this object is not a Drawable");

    Drawable* drawable = wrapper_drawable->drawable();

    if(!drawable)
        return context()->throwError(QScriptContext::TypeError, "Drawable.insertChildren: no Drawable wrapped");

    if(argumentCount() != 1)
        return context()->throwError(QScriptContext::SyntaxError, "Drawable.insertChildren takes exactly 1 argument");

    // TODO: maybe allow multiple arguments

    if(!argument(0).isNumber())
        return context()->throwError(QScriptContext::TypeError, "Drawable.insertChildren: argument 0 should be a number");

    unsigned int position = argument(0).toNumber();

    if(!argument(1).isNumber())
        return context()->throwError(QScriptContext::TypeError, "Drawable.insertChildren: argument 1 should be a number");

    unsigned int count = argument(1).toNumber();

    return engine()->toScriptValue(drawable->removeChildren(position, count));
}

QScriptValue Wrapper_Drawable::visibleChildren() const {
    Wrapper_Drawable* wrapper_drawable = qscriptvalue_cast<Wrapper_Drawable*>(context()->thisObject());

    if(!wrapper_drawable)
        return context()->throwError(QScriptContext::TypeError, "Drawable.children: this object is not a Drawable");

    Drawable* drawable = wrapper_drawable->drawable();

    if(!drawable)
        return context()->throwError(QScriptContext::TypeError, "Drawable.children: no Drawable wrapped");

    if(argumentCount() > 0)
        return context()->throwError(QScriptContext::SyntaxError, "Drawable.children does not take any argument");

    QList<Drawable*> drawables = drawable->visibleChildren();
    QList<Wrapper_Drawable*> wrapper_drawables;
    for(QList<Drawable*>::const_iterator it = drawables.constBegin(), end = drawables.constEnd();
        it != end; ++it)
    {
        wrapper_drawables.append(new Wrapper_Drawable(*it));
    }

    return engine()->toScriptValue(wrapper_drawables);
}

MeshDrawable:

#ifndef WRAPPER_MESHDRAWABLE_H
#define WRAPPER_MESHDRAWABLE_H

#include "wrapper_drawable.h"

#include "../meshdrawable.h"

class Wrapper_MeshDrawable : public Wrapper_Drawable
{
    Q_OBJECT
public:
    Wrapper_MeshDrawable(MeshDrawable* meshDrawable = 0, QObject *parent = 0);

    virtual MeshDrawable* drawable() const;

public slots:
    QScriptValue addTri();
    QScriptValue addQuad();
    QScriptValue setSmoothing();
};

Q_DECLARE_METATYPE(Wrapper_MeshDrawable*)

#endif // WRAPPER_MESHDRAWABLE_H

CPP:

#include "wrapper_meshdrawable.h"

Wrapper_MeshDrawable::Wrapper_MeshDrawable(MeshDrawable *meshDrawable, QObject *parent) :
    Wrapper_Drawable(meshDrawable, parent)
{
}

MeshDrawable* Wrapper_MeshDrawable::drawable() const {
    return static_cast<MeshDrawable*>(Wrapper_Drawable::drawable());
}

QScriptValue Wrapper_MeshDrawable::addTri() {

}

QScriptValue Wrapper_MeshDrawable::addQuad() {

}

QScriptValue Wrapper_MeshDrawable::setSmoothing() {

}

最后是 ScriptManager （我在其中向脚本引擎声明各种类型）：

#ifndef SCRIPTMANAGER_H
#define SCRIPTMANAGER_H

#include <QtScript/QScriptEngine>
#include <QtScriptTools/QScriptEngineDebugger>
#include <QtScriptTools/QtScriptTools>
#include <QStringList>
#include <QObject>

#include "utility.h"

class ScriptManager : public QObject {
    Q_OBJECT
public:
    ScriptManager();

public slots:
    QString interprete(QString command);

private:
    void initializeFunctions();

    QScriptEngine* m_scriptEngine;

    QScriptEngineDebugger* m_scriptEngineDebugger;
};

#endif // SCRIPTMANAGER_H

CPP

#include "scriptmanager.h"
#include "scenegraph.h"

#include "meshdrawable.h"
#include "objdrawable.h"

#include <QScriptValueIterator>

#include "wrappers/wrapper_camera.h"
#include "wrappers/wrapper_cameramanager.h"
#include "wrappers/wrapper_drawable.h"
#include "wrappers/wrapper_meshdrawable.h"
#include "wrappers/wrapper_drawablemanager.h"
#include "wrappers/wrapper_scenegraph.h"
#include "wrappers/wrapper_shadermanager.h"

QString ScriptManager::returnString = QString();

ScriptManager::ScriptManager() : m_scriptEngine(new QScriptEngine())
{
    initializeFunctions();
}

void ScriptManager::initializeFunctions() {
    qScriptRegisterQObjectMetaType<QGLShaderProgram*>(m_scriptEngine);

    qScriptRegisterSequenceMetaType<QList<Wrapper_Drawable*> >(m_scriptEngine);

    QScriptValue function_ls = m_scriptEngine->newFunction(scriptFunction_ls);
    m_scriptEngine->globalObject().setProperty("ls", function_ls);

    QScriptValue function_print = m_scriptEngine->newFunction(scriptFunction_print);
    m_scriptEngine->globalObject().setProperty("print", function_print);

//    m_scriptEngine->setDefaultPrototype(qMetaTypeId<Observer*>(),
//                                        Observer::getDefaultPrototype(m_scriptEngine));

    Wrapper_Drawable* wrapper_drawable = new Wrapper_Drawable();
    QScriptValue wrapper_drawable_obj = m_scriptEngine->newQObject(wrapper_drawable);
    m_scriptEngine->setDefaultPrototype(qMetaTypeId<Wrapper_Drawable*>(),
                                        wrapper_drawable_obj);
    m_scriptEngine->globalObject().setProperty("Drawable", wrapper_drawable_obj);

    Wrapper_MeshDrawable* wrapper_meshDrawable = new Wrapper_MeshDrawable();
    QScriptValue wrapper_meshDrawable_obj = m_scriptEngine->newQObject(wrapper_meshDrawable);
    m_scriptEngine->setDefaultPrototype(qMetaTypeId<Wrapper_MeshDrawable*>(),
                                        wrapper_meshDrawable_obj);
    m_scriptEngine->globalObject().setProperty("MeshDrawable", wrapper_meshDrawable_obj);

    Wrapper_Camera* wrapper_camera = new Wrapper_Camera();
    m_scriptEngine->setDefaultPrototype(qMetaTypeId<Wrapper_Camera*>(),
                                        m_scriptEngine->newQObject(wrapper_camera));

    Wrapper_CameraManager* wrapper_cameraManager = new Wrapper_CameraManager();
    m_scriptEngine->setDefaultPrototype(qMetaTypeId<Wrapper_CameraManager*>(),
                                        m_scriptEngine->newQObject(wrapper_cameraManager));

    Wrapper_DrawableManager* wrapper_drawableManager = new Wrapper_DrawableManager();
    m_scriptEngine->setDefaultPrototype(qMetaTypeId<Wrapper_DrawableManager*>(),
                                        m_scriptEngine->newQObject(wrapper_drawableManager));

    Wrapper_SceneGraph* wrapper_sceneGraph = new Wrapper_SceneGraph(SceneGraph::instance());
    m_scriptEngine->setDefaultPrototype(qMetaTypeId<Wrapper_SceneGraph*>(),
                                        m_scriptEngine->newQObject(wrapper_sceneGraph));

    QScriptValue object_sceneGraph = m_scriptEngine->newQObject("sceneGraph", wrapper_sceneGraph);
    m_scriptEngine->globalObject().setProperty("sceneGraph", object_sceneGraph);

    Wrapper_ShaderManager* wrapper_shaderManager = new Wrapper_ShaderManager();
    m_scriptEngine->setDefaultPrototype(qMetaTypeId<Wrapper_ShaderManager*>(),
                                        m_scriptEngine->newQObject(wrapper_shaderManager));

    m_scriptEngineDebugger = new QScriptEngineDebugger();
    m_scriptEngineDebugger->attachTo(m_scriptEngine);
}

Answer 1

您需要定义您的原型。这很快就会变得复杂，但是 http://doc.qt.io/archives/qt-4.7/scripting.html#making-use-of-prototype-based-inheritance 是一个很好的参考。