c++ - 哨兵 QWidget 是个好主意吗(在创建和填充布局时防止内存泄漏)？

Question

这段代码摘自 http://doc.qt.digia.com/qt/qhboxlayout.html#details是的，除了一些我不知道的魔法，充满了潜在的内存泄漏。

编辑:感谢 Nikos C. 指出 Qt 中的异常安全性很奇怪，如下所示:http://doc.qt.digia.com/qt/exceptionsafety.html因此，为了保持我的问题的主要意图有效，我更新了示例代码:

 QWidget *window = new QWidget;
 QPushButton *button1 = new QPushButton("One");
 QPushButton *button2 = new QPushButton("Two");
 QPushButton *button3 = new QPushButton("Three");
 QPushButton *button4 = new QPushButton("Four");
 QPushButton *button5 = new QPushButton("Five");

 QMyWidgetThatCanThrow *myWidget = new QMyWidgetThatCanThrow("");

 QHBoxLayout *layout = new QHBoxLayout;
 layout->addWidget(button1);
 layout->addWidget(button2);
 layout->addWidget(button3);
 layout->addWidget(button4);
 layout->addWidget(button5);
 layout->addWidget(myWidget);

 window->setLayout(layout);
 window->show();

只有在最后才将小部件重新分配给窗口，因此最后两行之前的任何异常都会泄漏所有内容(假设在真实代码中窗口有一个父窗口)。

在类似的非 Qt 代码中，我会使用哨兵对象来处理这种事情。是否有其他人在查看我的代码时会理解的使用哨兵的最佳实践方法？

编辑:这是可接受的设计模式吗？

void PopulateWindow(QWidget *window)
{
     QWidget sentry;    //serves as the intial parent ensuring that all
                        //widgets are either reparented or deleted
     QPushButton *button1 = new QPushButton("One",&sentry);
     QPushButton *button2 = new QPushButton("Two",&sentry);
     QPushButton *button3 = new QPushButton("Three",&sentry);
     QPushButton *button4 = new QPushButton("Four",&sentry);
     QPushButton *button5 = new QPushButton("Five",&sentry);

     QHBoxLayout *layout = new QHBoxLayout(&sentry);
     layout->addWidget(button1);
     layout->addWidget(button2);
     layout->addWidget(button3);
     layout->addWidget(button4);
     layout->addWidget(button5);

     window->setLayout(layout);
}    //sentry goes out of scope and deletes anything that was not reparented

使用它:

 QWidget *window = new QWidget;
 PopulateWindow(window);
 window->show();

Answer 1

什么地方可能出错？你想避免什么问题？如果你创建了小部件并且有任何东西迫使你中止，就像你在常规 C/C++ 中做的那样

if(huhOh!!){
   delete button1;
   delete button2;
   ....
   return false
}

编辑:

没有什么能阻止你做

void PopulateWindow(QWidget *window){

 QPushButton *button1 = new QPushButton("One",window);
 QPushButton *button2 = new QPushButton("Two",window);
 QPushButton *button3 = new QPushButton("Three",window);
 QPushButton *button4 = new QPushButton("Four",window);
 QPushButton *button5 = new QPushButton("Five",window);

 QHBoxLayout *layout = new QHBoxLayout(window);
 layout->addWidget(button1);
 layout->addWidget(button2);
 layout->addWidget(button3);
 layout->addWidget(button4);
 layout->addWidget(button5);

 //layout already set
 //window->setLayout(layout);
}  

在这种情况下，您只需删除 window