Using uic generated classes as a base class in public API

Richard Dale Richard_Dale at
Wed Mar 2 22:58:02 UTC 2005

On Wednesday 02 March 2005 17:32, Matt Rogers wrote:
> Hi,
> It's a huge mistake to use classes generated by uic in public API. The
> reason for this is that uic generated classes lack virtual destructors.
> Without virtual destructors, derived class destructors are never called,
> and then leak memory, objects don't get deleted properly, in essence,
> you're screwed.
Typically subclasses of a uic base class don't use any resources that need to 
be freed in the destructor. Can you show an example of some code which does 
leak memory?

> Since, AFAIK, the kdevelop project as a whole doesn't care about BC, we
> need to fix the classes that use a uic generated class as a base class. I
> first noticed the problem in languages/lib/designer_integration but i
> imagine it's elsewhere too.
> Here's how we fix it:
> - Change the classes that have a uic generated class as a base class to
> store a pointer to the uic generated class instead.
> - Make the base class derive from the appropriate widget.
> - Convert any uic generated class that's not a QWidget (i.e. QDialog or
> similar, to QWidget) to a QWidget
> I'll leave languages/lib/designer_integration to adymo, but will try to go
> through kdevelop and change the other relevant classes throughout the week.
This seems to be a major change to solve a problem which I don't believe 
exists. Have you measured any memory leaks?

-- Richard

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