super constructors: I can't take it anymore!

Regan Heath regan at
Wed Aug 16 06:02:56 PDT 2006

On Wed, 16 Aug 2006 15:15:49 +0300, Serg Kovrov <kovrov at no.spam> wrote:
> * Oskar Linde:
>> Or, you can reconsider your design. One option is to make a register()  
>> method that only the BaseWindow constructor calls. In you child  
>> classes, you can overload the register() method anyway you wish.
> Yes, I thought about reconsider design to workaround this issue, but I  
> can't find clean solution yet.
> Let me clear my design. Obvious hierarchy - a base class for common  
> any-window functionality, and subclasses for common window cases (such  
> top frame, button, reac hedit, etc) which may have more narrow but still  
> generic, and finally end-user-classes for particular application.
> All windows classes must register (once) os class with its window  
> procedure, and create a os window *when instancing*. That is one thing I  
> do not want to change. e.g, when I do `new Button("push me")` I have  
> button object ready for action. no need/worry to init it, it should be  
> inited in constructor.
> Ok, next. I want unique window procedure for each 'generic' window  
> class. eg BaseWindow FrameWindow, Probably I need to explain more, but  
> do not want to bloat this message. In few words it is for performance  
> reasons. And that approach I'd like to keep too.
> My original idea was - each of constructors call register() and create()  
> methods with different parameters - window procedure callback and window  
> classname.

How's this?

import std.stdio;

typedef int function(int i) WNDPROC;

class BaseWindow
	void register(char[] cname) { writefln("register(",cname,")"); }
	void create(int function(int) f) { writefln("create(",f(1),")"); }
	char[] classname() { return "BaseWindow"; }
	WNDPROC windproc() { return cast(WNDPROC)function int(int i){return i;}; }
	this() { register(classname()); create(windproc()); }

class FrameWindow : BaseWindow
	override char[] classname() { return "FrameWindow"; }
	override WNDPROC windproc() { return cast(WNDPROC)function int(int  
i){return i*2;}; }

void main()
	FrameWindow b = new FrameWindow();
	BaseWindow a = new BaseWindow();


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