Qt:是否“新建而不删除"?使用控件导致内存泄漏?
我正在查看 Qt 示例 此处::>
在构造函数中,它们有:
Window::Window(){编辑器 = 新 QTextEdit();//内存泄漏?QPushButton *sendButton = new QPushButton(tr("&Send message"));//内存泄漏?连接(发送按钮,信号(点击()),这个,插槽(发送消息()));QHBoxLayout *buttonLayout = new QHBoxLayout();//内存泄漏?buttonLayout->addStretch();buttonLayout->addWidget(sendButton);buttonLayout->addStretch();QVBoxLayout *layout = new QVBoxLayout(this);//内存泄漏?布局-> addWidget(编辑器);布局-> addLayout(buttonLayout);setWindowTitle(tr("自定义类型发送"));}
那些带有注释的行
//内存泄漏?
那些不是内存泄漏吗?
如果是这样,既然 Window 类没有构造函数,那么我应该让所有这些变量(编辑器已经是)Window 成员变量?
或者..Qt 是否会在超出范围时在内部删除"这些成员变量?
解决方案从 C++14 开始,您可以使用 std::make_unique()
方便的函数模板,用于创建 std::unique_ptr<>
拥有小部件的独家所有权.然后,在将小部件传递给 addLayout()
的那一刻,您通过调用 release()
使智能指针放弃所有权:
auto buttonLayout = std::make_unique();//...//这里可能会抛出异常//...布局-> addLayout(buttonLayout.release());
I was looking at Qt example here:
and inside the constructor, they have:
Window::Window()
{
editor = new QTextEdit(); // Memory leak?
QPushButton *sendButton = new QPushButton(tr("&Send message")); // Memory leak?
connect(sendButton, SIGNAL(clicked()), this, SLOT(sendMessage()));
QHBoxLayout *buttonLayout = new QHBoxLayout(); // Memory leak?
buttonLayout->addStretch();
buttonLayout->addWidget(sendButton);
buttonLayout->addStretch();
QVBoxLayout *layout = new QVBoxLayout(this); // Memory leak?
layout->addWidget(editor);
layout->addLayout(buttonLayout);
setWindowTitle(tr("Custom Type Sending"));
}
Those lines with comments
// Memory leak?
aren't those memory leaks?
If so, since the Window class has no constructor, then I should make all of those variables (editor already is) Window member variables ?
Or..does Qt internally "delete" those member variables when it goes out of scope?
解决方案As of C++14 you can use the std::make_unique()
convenience function template for creating an std::unique_ptr<>
that has exclusive ownership of the widget. Then, at the moment of passing the widget to addLayout()
, you make the smart pointer give up ownership by calling release()
:
auto buttonLayout = std::make_unique<QHBoxLayout>();
// ...
// an exception could be thrown here
// ...
layout->addLayout(buttonLayout.release());
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