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Date: 12 Apr 92 18:19:02 GMT
From: widget!jgg@uunet.uu.net  (Xmiester)
Subject: Re: Ada multitasking with X-windows
Message-ID: <1992Apr12.181902.4917@widget!uunet.uu.net>
List-Id: <comp.lang.ada>

dwb@IMD.Sterling.COM (David Boyd) writes:

[... read earilier news posts on comp.windows.x to get the preliminaries ...]

>
>	And the government wants to know why developing X applications
>in Ada costs so much!!  
>
Compared to what?  Who has been doing this complaining?  I've been
searching for this information, but have yet been able to find any.

>I am old enough to remember the tail end of JOVIAL
>(a previous government developed language) and someone asking us to develop
>bindings between our FORTRAN libraries and JOVIAL.  The problems were very
>similar and the solutions equally ugly in many cases and JOVIAL was not as
>different from FORTRAN as Ada is from C.  
>

The currently available commercial Ada/Motif bindings can hardly be
called ugly.  They are as clean (or cleaner) than the C interface
with stronger type checking.  (Can you say "pragma External" ?)

>
>	The solution is for someone to
>completely re-implement not only the X library and intrinsics with a
>design geared toward Ada but the GUIs libraries (OLIT & MOTIF) as well.
>

I hardly believe this is a cost effective solution.  The answer is *NOT*
to re-invent a *better* wheel w/o a justification for the cost.  The
majority of Ada projects can deal with non-reentrant X/Xt/Motif libs.
It just requires knowledge and good design to do it right.  I suggest
that a better spent dollar is in the training of Ada engineers on the
issues and how to deal with them effectively from an engineering standpoint.
(It's surprising how many Ada programmer's I meet who write multi-tasking
 software, but don't understand the issues involved in writing re-entrant
 code, providing tasking-safe data structures, or real-time software in
 general).


I've been involved in the proposed design for an Ada widget set.
It ended up coming surprisingly close to the Xt single inheritance
model minus the added features of Xt/Motif such as the event translation
manager, keyboard traversal, etc... (due to $$$ considerations :-)

(BTW, the Ada9X inheritance proposal is a near duplicate of
the Xt single inheritance model -- It's how we've done it for years
in a more formalized definition, that's all).  Not that I'm saying the
Xt inheritance model is *great* but it's how you do it by hand in
a language which doesn't support inheritance.  (ie. it's optimally sufficient)

MOTTO: Do not what has been done, but understand it and use it.


-- 
John Goodsen
goodsenj@ajpo.sei.cmu.edu

-- 
John Goodsen
goodsenj@ajpo.sei.cmu.edu