Re: [Fxruby-users] questions about the wrapper code of fxruby

[Lyle J. <ly...@kn...>]

On Apr 4, 2004, at 3:25 PM, meinrad recheis wrote:

> i studied the FXRuby src and interfaces, because i am going to wrap 
> some C++ modules derived from Fox classes for ruby.

OK.

> i am quite new to "wrapping" and SWIG so i would like to ask you the 
> things that the SWIG docu left unclear to me:
>
> * why did you prefer writing whole "shadow classes" (i.e FXRbGLCanvas 
> for FXGLCanvas) rather than using SWIG's typemaps?
> * the /FX*Virtuals/ confuse me; why is "re-declaration" of virtual 
> functions necessary?

Both of these are for the same fundamental reason: I wanted the Ruby 
programmer to be able to override the virtual functions declared in C++ 
base classes. For example, if you subclass FXMainWindow to make your 
own main window class:

	class MyMainWindow < FXMainWindow
	end

and then override the base class create() method with one of your own:

	def create
		super
		puts "Here I am, in MyMainWindow#create!"
	end

this should work exactly as it would in the corresponding C++ code. 
That is, if you were to construct an instance of your main window class 
and then call the application's create() method:

	myMainWin = MyMainWindow.new(theApp, ...)
	theApp.create

It should land in your overridden version of create() instead of 
FXMainWindow#create.

As of the latest SWIG development versions, this capability is built-in 
using the so-called "director classes" feature; but it was not 
available in SWIG when I first started developing FXRuby several years 
ago.

Hope this helps,

Lyle