Thread: Derived Constructor Question

Perhaps you could reduce the number of arguments with a Rectangle class (x, y, w, z)? Otherwise, perhaps the Widget constructor has other side-effects besides just setting data values?

I'd pass title by const-reference there. However, does the title need to be set from the beginning? You could make it the last parameter and default it to empty string, and then provide a SetTitle method. That would give you one less argument sometimes.

Originally Posted by Jimage

Is there a cleaner way to call a class's constructor when declaring a class derived from it without having to redeclare all its parameters?

So far this is the most suitable solution I've figured out:

Code:

class Widget
  Widget(int x, int y, int w, int h) { ... }
  Widget(Widget* _Widget) { x = _Widget->x; ... }

class w_Button:public Widget
  w_Button(string title, int type, Widget _Widget):Widget(_Widget) { ... }

As opposed to:

Code:

  w_Button(string title, int type, int _x, int _y, int _w, int _h):Widget(_x,_y,_w,_h) { ... }

This way, with c++0x I can just go:

Code:

new w_Button("Test", BUTTON_TEST, {10,10,32,10});

So I guess I'm wondering if there's anything sneaky built into either c++ or c++0x that cuts out the need to make a temporary instance of the base class and send a second set of parameters directly to the base constructor.

Or some other solution I'm completely overlooking.

Define a class/structure to hold the parameters and just pass that down the chain. Otherwise, I can't think of a very practical way to do that, honestly...