Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!mcsun!unido!tub!net
From: net@tub.UUCP (Oliver Laumann)
Newsgroups: comp.windows.news
Subject: Re: Toolkits, toolkits, toolkits ...
Message-ID: <1132@tub.UUCP>
Date: 4 Jan 90 15:05:32 GMT
References: <7391@ficc.uu.net> <634@s5.Morgan.COM> <4572@hplabsz.HPL.HP.COM>
Reply-To: net@tub.UUCP (Oliver Laumann)
Organization: Technical University of Berlin, Germany
Lines: 58

In article <4572@hplabsz.HPL.HP.COM> mayer@hplabs.hp.com (Niels Mayer) writes:
> In article <634@s5.Morgan.COM> jordan@Morgan.COM (Jordan Hayes) writes:
> >	But first make the easy things easy. "Hello World" in a
> >	windowing system shouldn't be more than 10 lines of code.
> >Sigh.  When will people learn to code before blabing on USENET?
> >This is in Motif ...
> 
> Well, you can easily do a "hello world" in WINTERP in less than 10 lines.

[Example program and WINTERP blurb deleted]

This is how you would write it in `Elk' Scheme:

;;; -*-Scheme-*-

(require 'xwidgets)
(load-widgets shell label)

(let* ((con (create-context))
       (dpy (initialize-display con 'kraftbus:0 'hello 'demo))
       (top (create-shell 'hello 'demo (find-class 'application-shell) dpy))
       (w (create-managed-widget (find-class 'label) top
				 'label "Hello world")))
  (realize-widget top)
  (context-main-loop con))


Note that the initialization of the application context and display
is somewhat lengthy (by the way, I wonder why the initialization is
missing in the WINTERP example).  `kraftbus' is the name of the
workstation on my desk (yes, the name is weird, if you want me to
tell you the anecdote behind it, drop me a letter), so `kraftbus:0'
obviously is the display name.  One can use #f instead to indicate
that the value of the $DISPLAY environment variable is to be used.

The `require' form loads the Elk interface to the Xlib, Xt, and the
Athena widget set (one would write "(require 'motif)" to load the
interface to the OSF/Motif widgets).  `find-class' creates a Scheme
object of type `widget class' (widget classes are, like widgets and
application contexts, first class objects).

If the example had used the Athena command widget, one could have
added a callback like this:

   (add-callback w 'callback
     (lambda (widget)
          ; do something
       ))

or, using set-values!,
  
   (set-values! w 'callback
     (list
       (lambda (widget)
	 ...)))

--
Oliver Laumann              net@TUB.BITNET              net@tub.UUCP