[Qt-interest] QObject destructor

[Nikos Chantziaras]

On 05/04/2010 10:50 PM, Nikos Chantziaras wrote:
> On 05/04/2010 10:43 PM, Yifei Li wrote:
>> Hi folks,
>>
>> I'm wondering if QObject destructor will delete the object's
>> children.
>>
>> For example, I have my own class MyWidget, and in its constructor
>> widgets are created on the stack with parent being the MyWidget
>> object. So do I need to delete all the widgets created on the stack
>> in MyWidget's destructor?
>
> Don't create widgets on the stack if they have a parent. Never.
> ~QObject() will try to delete them, and since they're on the stack, this
> will bomb at some point.

I should have provided more detail here.  The correct phrase would be:

   Don't create widgets on the stack if they have a parent *and
   the parent is deleted before the children go out of scope*.

For example, this is not OK:

   QWidget* parent = new QWidget;
   QWidget child(parent);
   delete parent;

However, this is OK:

   QWidget* parent = new QWidget;
   {
     QWidget child(parent);
   }
   delete parent;

That's because when 'child' goes out of scope, its destructor will 
remove it from its parent's child list.