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Re: Fwd: Stack vs. Heap

Subject: Re: Fwd: Stack vs. Heap
From: Lars Knoesel
Date: Mon, 13 Aug 2007 19:26:14 +0200
* On 13.08.2007 15:20, Daniel Albuschat wrote:

[...]
Here's the way I do it, which is, imho, conceptually better:

class MyWidget: public QWidget
{
   Q_OBJECT
private:
   QLineEdit   le_name;
   QLabel      l_name;
   QVBoxLayout layout;
public:
   MyWidget(QWidget *parent):
      QWidget(parent),
      le_name(0),
      l_name(0) {

      l_name.setText("Name: ");
      layout.addWidget(&l_name);
      layout.addWidget(&le_name);
      setLayout(&layout);
   }
};

But the stack order seems to be very important. My example leads to an
segmentation fault when the window is destroyed. The solution is to
transpose the two variables below.

class MyWidget : public QWidget
{
    Q_OBJECT

    QGridLayout m_innerLayout;
    QGroupBox   m_groupBox;

 public:
    MyWidget(QWidget* = 0);
    virtual ~MyWidget();
};
MyWidget::MyWidget(QWidget* a_parent)
    : QWidget(a_parent),
      m_innerLayout(0),
      m_groupBox(0)
{

    m_groupBox.setLayout(&m_innerLayout);
}

Regards,

Lars

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