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<H1>[MUD-Dev] Re: DevMUD:  Inheritable modules</H1>
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<LI><em>To</em>: <A HREF="mailto:mud-dev#kanga,nu">mud-dev#kanga,nu</A></LI>
<LI><em>Subject</em>: [MUD-Dev] Re: DevMUD:  Inheritable modules</LI>
<LI><em>From</em>: James Wilson &lt;<A HREF="mailto:jwilson#rochester,rr.com">jwilson#rochester,rr.com</A>&gt;</LI>
<LI><em>Date</em>: Fri, 30 Oct 1998 18:17:21 -0500</LI>
<LI><em>Reply-To</em>: <A HREF="mailto:mud-dev#kanga,nu">mud-dev#kanga,nu</A></LI>
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<PRE>

[Jon Leonard]
&gt;&gt; &gt;I don't want to use C++, because it doesn't have the object model I want.

[James]
&gt;&gt; can you elaborate?

&gt;More or less what I've said in other messages.  You can't change the
&gt;implementation of a base class without (usually) forcing a recompile, you
&gt;can't query objects for what methods they support, you need to know object
&gt;interfaces at compile time.  That sort of thing.

okay. of these, only the last do I disagree with - not because you're wrong, 
but because I think it's a GOOD thing. That is, when I compile something
in C++, I know that the compiler will tell me if I'm trying to invoke
methods on objects that don't support them. The alternative would be to 
allow foo-&gt;bar () even if foo isn't known to support method bar (), and
throwing an exception (or something) at runtime. This sounds like a nightmare
of intermittent errors to me, but then I'm a big strong-typing fanatic.
 
&gt;You can do these things in C++, but you wind up doing it in parallel with
&gt;the C++ module hierarchy.  Why not do it in a language-portable way?

hmmm, yes, I mainly agree. This does raise the question, though, of _what_
languages and how. If C and C++ are to interoperate, this is straightforward
and we can write the kernel in either one, object model aside. I am dubious
about the possibility of having other languages cooperate without some
heavyweight abstraction such as CORBA or Gamora's buses. That doesn't mean I'm
necessarily against such a thing, I'm just concerned about efficiency.

What are people's thoughts on this? Should we try to come up with something 
"language agnostic", as the Casbah project (built on Gamora - see Nick's post
of his communique from the Gamora guy for a pointer) is attempting to do using
Scheme? There were some interesting messages on their mailing list about
troubles they were having with language agnosticism, which I will attempt to
find again and post to mud-dev.

&gt;&gt; did you see my proposal for how this could be done very easily in C++? the
&gt;&gt; mapping is pretty straightforward.
&gt;
&gt;The recent one with the modules full of declarations, not the earlier post
&gt;about using extern "C"?  I've read all of the messages on MUD-Dev about
&gt;DevMUD (usually several times -- it's hard to remember everything reading it
&gt;only once.)
&gt;
&gt;It looked plausible, but my primary point is that if we're going to invent
&gt;a different model to deal with dlopen sorts of issues, we should invent one
&gt;that works for C, C++, or nearly any other language.  I prefer to write
&gt;modules in C, and if someone else writes in C++, we should interoperate.

there's nothing in what I proposed that would prevent that. Just write a C++
stub for your C functions and export that as a named interface. Your scheme
using void function pointers and mangled names requires C++ modules to write a
series of C stubs for their methods, so neither scheme is more general. Perl,
Python, Java etc all can bind to C++ as well as to C, so there's no difference
there. But I think we're putting the cart before the horse.

We need to step back a little bit and talk about goals. Are we looking
for language agnosticism? Anything with C/C++ bindings? Distributed
processing? I think these questions need to be answered before we can talk
about intermodule protocols.

James


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<li><strong><A NAME="00682" HREF="msg00682.html">[MUD-Dev] Re: DevMUD:  Inheritable modules</A></strong>
<ul compact><li><em>From:</em> Jo Dillon &lt;emily#thelonious,new.ox.ac.uk&gt;</li></ul>
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<ul><li>Thread context:
<BLOCKQUOTE><UL>
<LI><STRONG>[MUD-Dev] Re: DevMUD:  Inheritable modules</STRONG>, <EM>(continued)</EM>
<ul compact>
<ul compact>
<LI><strong><A NAME="00579" HREF="msg00579.html">[MUD-Dev] Re: DevMUD:  Inheritable modules</A></strong>, 
The Arrow <a href="mailto:arrow#trelleborg,mail.telia.com">arrow#trelleborg,mail.telia.com</a>, Thu 29 Oct 1998, 17:56 GMT
<UL>
<LI><strong><A NAME="00583" HREF="msg00583.html">[MUD-Dev] Re: DevMUD:  Inheritable modules</A></strong>, 
Jon Leonard <a href="mailto:jleonard#divcom,slimy.com">jleonard#divcom,slimy.com</a>, Fri 30 Oct 1998, 00:48 GMT
<UL>
<LI><strong><A NAME="00584" HREF="msg00584.html">[MUD-Dev] Re: DevMUD:  Inheritable modules</A></strong>, 
James Wilson <a href="mailto:jwilson#rochester,rr.com">jwilson#rochester,rr.com</a>, Fri 30 Oct 1998, 02:14 GMT
<UL>
<LI><strong><A NAME="00602" HREF="msg00602.html">[MUD-Dev] Re: DevMUD:  Inheritable modules</A></strong>, 
Jon Leonard <a href="mailto:jleonard#divcom,slimy.com">jleonard#divcom,slimy.com</a>, Fri 30 Oct 1998, 22:18 GMT
<UL>
<LI><strong><A NAME="00604" HREF="msg00604.html">[MUD-Dev] Re: DevMUD:  Inheritable modules</A></strong>, 
James Wilson <a href="mailto:jwilson#rochester,rr.com">jwilson#rochester,rr.com</a>, Fri 30 Oct 1998, 23:58 GMT
<UL>
<LI><strong><A NAME="00682" HREF="msg00682.html">[MUD-Dev] Re: DevMUD:  Inheritable modules</A></strong>, 
Jo Dillon <a href="mailto:emily#thelonious,new.ox.ac.uk">emily#thelonious,new.ox.ac.uk</a>, Mon 02 Nov 1998, 10:17 GMT
<UL>
<LI><strong><A NAME="00696" HREF="msg00696.html">[MUD-Dev] Re: DevMUD:  Inheritable modules</A></strong>, 
James Wilson <a href="mailto:jwilson#rochester,rr.com">jwilson#rochester,rr.com</a>, Tue 03 Nov 1998, 03:18 GMT
</LI>
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</UL>
</LI>
<LI><strong><A NAME="00592" HREF="msg00592.html">[MUD-Dev] Re: DevMUD:  Inheritable modules</A></strong>, 
Niklas Elmqvist <a href="mailto:d97elm#dtek,chalmers.se">d97elm#dtek,chalmers.se</a>, Fri 30 Oct 1998, 13:15 GMT
<UL>
<LI><strong><A NAME="00596" HREF="msg00596.html">[MUD-Dev] Re: DevMUD:  Inheritable modules</A></strong>, 
Jon Leonard <a href="mailto:jleonard#divcom,slimy.com">jleonard#divcom,slimy.com</a>, Fri 30 Oct 1998, 17:20 GMT
</LI>
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