Derive UIC generated Qt UI class from custom interface - qt

Question

I've a simple Qt Question. I want that automatically generated UIC files are derived from a custom interface class like in:
Intention
class MyUiInterface {
public:
virtual void setupUi(QWidget* w) = 0;
virtual void retranslateUi(QWidget*w) = 0;
};
Generated UIC file should look like:
class Ui_MyWidget {
public:
void setupUi(QWidget* w) {
...
}
void retranslateUi(QWidget* w) {
...
}
};
namespace Ui {
class MyWidget : public MyUiInterface , public Ui_MyWidget {};
}
Why?
Every Ui::Class would then implement MyUiInterface. In each class that derives from Ui::Class (see The Multiple Inheritance Approach) I would be able to call setupUi and retranslateUi which makes sense if the class that derives from UI::Class class is a base class either. I want every widget to be derived from my abstrcat base class MyWidgetBase. Consider following:
class MyWidgetBase abstract : public QWidget, protected MyUiInterface {
protected:
void changeEvent(QEvent *e) {
QWidget::changeEvent(e);
if (e->type() == QEvent::LanguageChange) {
retranslateUi(this); // Still abstract here
}
}
};
class MyWidget : public MyWidgetBase : public Ui::MyWidget {
};
The effect is, every time MyWidget::changeEvent() is callled, retranslateUi of that specific class is called. Otherwise changeEvent had to be reimplemented in each class. This would be a bit against "code reuse" concept.
I think Qt UIC is not able to handle this situation isn't it? Is there a similar way to solve this problem?

Answer 1

Unfortunately, reading XML Schema for ui files is telling us that this is not possible to automate using uic compiler.
However, it is unclear to me why you would want to implement that automatically - even if the Uic somehow manages to implement your interface, you will still need to add bodies of the functions by hand, editing generated .h file, as I am sure that there is no way to include custom code in xml file which will translate as C++ code.
Why you just don't reimplement setupUi and retranslateUi in your MyWidget class? Every Ui class will have one of these classes, so you can implement this on this level, instead of base class. It is possible that I am missing something, but I see this as an appropriate way to do this.
class MyWidget : public MyWidgetBase, public Ui::MyWidget {
public:
void setupUi(QWidget* w) {
...
}
void retranslateUi(QWidget* w) {
...
}
};
With this approach, you don't need to reimplement changeEvent() in any of your custom widgets, and changeEvent will still call the appropriate retranslateUi().