what does the constructor do here?

[squidge]

You can use whatever code you like in the constructor, in this case various widgets are added depending on the value to pass to the constructor.

For example, if you pass ButtonWidget::ComboBoxes, then you get ComboBoxes, if you pass ( ButtonWidget::ComboBoxes | ButtonWidget::SpinBoxes) then you'll get boith ComboBoxes and SpinBoxes, etc.

If you really wanted to you could write an entire application in your constructor, but its not best practice to do so.

[LB4229]

thank you. I thought the constructor would be used only for initialization.
Your explanation enlightens me.

[ChrisW67]

The constructor is only used for initialisation in the ButtonWidget. The 'widget' parameter is used to drive how the ButtonWidget is initialised using other methods (comboBoxes() etc.) in the class.

[Santosh Reddy]

Added to what squidge said, constructor is basically a special function which is called (automatically, compiler generates the required code) when object is created, you can do all the things in it which you could do in normal function, added to normal function constructors can take initialization list. Also there types of constructors like default constructor, copy constructor etc. which are beyond the scope of this post.