Subj : Re: wxWidgets
To   : comp.programming
From : Rob Thorpe
Date : Tue Jul 05 2005 01:05 pm

Phlip wrote:
> Rob Thorpe wrote:
>
> > My point is that it wxWindows would be much more useful if it was a
> > library providing a set of library calls.  That way it could be used
> > with any language.    Object-orientated wrappers could be written for
> > C++ and other OO languages.
>
> Technically, that paragraph betrays the belief that flat API functions are
> easier to bind to any language than OO objects are.
>
> Where this is true (and where we don't need Yet Another ORB-Oriented GUI
> Toolkit), others have discussed the wrapping issues.
>
> When I code in wxWidgets, I think "Ah ha, I'm smarter than all these lessor
> programmers. They think you 'reuse' an object in OO by inheriting its class!
> But I'm smart enough to know that most reuse is by delegation, so I won't
> inherit this Window class, I'l just make it a member of my application
> object!"
>
> Then to do anything with the window, I must override a virtual method. So I
> must switch to inheritance.
>
> That's what you meant by "force the user to use C++ and the
> object-orientated paradigm".

Yes.  Once inheritance and virtual functions are involved - which
normally has to be fairly early on in C++, you're stuck thinking like
they're thinking.

> What's really going on here is C++ is not "object oriented" /enough/. The
> best OO languages support block closures, which are the best way to sink
> events. I should be able to tell that window's event to call this code
> block. Without that feature, GUI Toolkits require linguistic hacks to sink
> events. Some toolkits call callback functions, and some call virtual
> methods. Either way, we got polymorphism.
>
> Someday, we will have an Ultimate GUI Toolkit when we have a cross-language
> system to permit block closures. Then all GUIs would be sets of library
> calls, and any language could call them, and sink their events.
>
> Flat API functions are stack-oriented. When we invent a block closure system
> that works at the binary level, the same for every language, then we can
> have an Ultimate GUI Toolkit.

I would like it very much if the GUI toolkit I was talking about were
to use closures.  It would make a great deal of code much simpler.
When I wrote my post I possibly wasn't dreaming hard enough.

The problem though is that it could be difficult generally, if the
function being closed within the scope is written in a different
language to the scope.    When this problem is solved, then yes the
Ultimate GUI toolkit is close.

.