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<H1>[MUD-Dev] Re: PDMud thread summary</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: PDMud thread summary</LI>
<LI><em>From</em>: Niklas Elmqvist &lt;<A HREF="mailto:d97elm#dtek,chalmers.se">d97elm#dtek,chalmers.se</A>&gt;</LI>
<LI><em>Date</em>: Mon, 26 Oct 1998 00:22:18 +0100 (MET)</LI>
<LI><em>Reply-To</em>: <A HREF="mailto:mud-dev#kanga,nu">mud-dev#kanga,nu</A></LI>
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<PRE>
On Sun, 25 Oct 1998, James Wilson wrote:
&gt; On Sun, 25 Oct 1998, Niklas Elmqvist wrote:
&gt;
&gt; &gt;class CallPipe : public Pipe {
&gt; &gt;private:
&gt; &gt;	FunctionPtr *hFun1, *hFun2;
&gt; &gt;public:
&gt; &gt;	..
&gt; &gt;	virtual void Send(ModuleID hSrc, ModuleID hDst, Message *hMsg);
&gt; &gt;	virtual void Recv(..)
&gt; &gt;	..
&gt; &gt;}
&gt; &gt;
&gt; 
&gt; [other kinds of Pipes snipped]
&gt; 
&gt; thanks for the example, it made things much clearer. the pattern
&gt; here is asynchronous message-passing, as found in, for instance, 
&gt; PVM, which is well-suited to highly decoupled parallel systems. 
&gt; If this is what people want, PVM already does this beautifully and
&gt; there's even a distributed FS for it. 

Well, I would argue that there are other servers which do MUDs quite
beautifully. Why do we need DevMUD, then? 

&gt; However, message-passing like this adds considerable programming
&gt; complexity to simple operations. Every function call into other modules
&gt; has to be done as Send and Recv pairs, where the next Message Recv'd
&gt; isn't necessarily what you wanted: 
&gt; 
&gt; /* try to get object 'foo' */
&gt; 
&gt; g_mainbus-&gt;Send (module_a, DB_MODULE, /* deliver foo or else! */);
&gt; Message *gotfoo = g_mainbus-&gt;Recv (module_a);
&gt; 
&gt; /* simultaneously, in some other meddling module... */
&gt; 
&gt; g_mainbus-&gt;Send (module_meddler, module_a, /* you go to hell! */);
&gt; 
&gt; so, back in module_a, we get 'you go to hell!' instead of 'foo'.
&gt; Checking this on EVERY FUNCTION CALL would get quite tedious
&gt; and add a performance hit. Moreover it's more prone to breakage
&gt; by newbie module-programmers for whom parallel systems are
&gt; mysterious.

Okay. I see your point. But if we want distribution, we need this anyway.
*shrug*

And yes, I am starting to hear your arguments here. I always thought a
pipe-like mechanism would be a very nice O-O abstraction for my own MUD
(although I at first envisioned something Chris Gray so aptly named "water
sprinkler"), but what you are saying is starting to make sense. The moral
of this story is: "abstraction is good, but to a degree only", a slightly
revamped version of my initial statement. 

But please let us contain function pointers as function objects. It
not only looks cleaner to my O-O sensitive eyes, that way, we can also
easily subclass them and add state for some reason. (Of course, since I
have not thought this through, I may be rambling :)  

&gt; I fully agree that abstractions are important. This seems like rather
&gt; an extreme way to do it though, which to me is only really justified
&gt; in a distributed system.

Agreed.

&gt; James

-- Niklas Elmqvist (d97elm#dtek,chalmers.se) ----------------------
  "The trouble with being a god is that you've got no one to 
   pray to."
		-- Terry Pratchett, Small Gods



</PRE>

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<UL><LI><EM>From:</EM> James Wilson &lt;jwilson#rochester,rr.com&gt;</LI></UL></LI>
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<ul><li>Thread context:
<BLOCKQUOTE><UL>
<LI><STRONG>[MUD-Dev] Re: PDMud thread summary</STRONG>, <EM>(continued)</EM>
<ul compact>
<ul compact>
<LI><strong><A NAME="00470" HREF="msg00470.html">[MUD-Dev] Re: PDMud thread summary</A></strong>, 
James Wilson <a href="mailto:jwilson#rochester,rr.com">jwilson#rochester,rr.com</a>, Sun 25 Oct 1998, 02:02 GMT
</LI>
</ul>
<LI><strong><A NAME="00492" HREF="msg00492.html">[MUD-Dev] Re: PDMud thread summary</A></strong>, 
Chris Gray <a href="mailto:cg#ami-cg,GraySage.Edmonton.AB.CA">cg#ami-cg,GraySage.Edmonton.AB.CA</a>, Sun 25 Oct 1998, 17:28 GMT
<UL>
<LI><strong><A NAME="00495" HREF="msg00495.html">[MUD-Dev] Re: PDMud thread summary</A></strong>, 
Niklas Elmqvist <a href="mailto:d97elm#dtek,chalmers.se">d97elm#dtek,chalmers.se</a>, Sun 25 Oct 1998, 19:45 GMT
<UL>
<LI><strong><A NAME="00498" HREF="msg00498.html">[MUD-Dev] Re: PDMud thread summary</A></strong>, 
James Wilson <a href="mailto:jwilson#rochester,rr.com">jwilson#rochester,rr.com</a>, Sun 25 Oct 1998, 21:10 GMT
<UL>
<LI><strong><A NAME="00502" HREF="msg00502.html">[MUD-Dev] Re: PDMud thread summary</A></strong>, 
Niklas Elmqvist <a href="mailto:d97elm#dtek,chalmers.se">d97elm#dtek,chalmers.se</a>, Mon 26 Oct 1998, 00:09 GMT
</LI>
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</LI>
</UL>
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</LI>
<LI><strong><A NAME="00499" HREF="msg00499.html">[MUD-Dev] Re: PDMud thread summary</A></strong>, 
Chris Gray <a href="mailto:cg#ami-cg,GraySage.Edmonton.AB.CA">cg#ami-cg,GraySage.Edmonton.AB.CA</a>, Sun 25 Oct 1998, 21:51 GMT
<UL>
<LI><strong><A NAME="00501" HREF="msg00501.html">[MUD-Dev] Re: PDMud thread summary</A></strong>, 
Niklas Elmqvist <a href="mailto:d97elm#dtek,chalmers.se">d97elm#dtek,chalmers.se</a>, Sun 25 Oct 1998, 23:08 GMT
<UL>
<LI><strong><A NAME="00506" HREF="msg00506.html">[MUD-Dev] Re: PDMud thread summary</A></strong>, 
Jon A. Lambert <a href="mailto:jlsysinc#ix,netcom.com">jlsysinc#ix,netcom.com</a>, Mon 26 Oct 1998, 02:54 GMT
<UL>
<LI><strong><A NAME="00513" HREF="msg00513.html">[MUD-Dev] Re: PDMud thread summary</A></strong>, 
Alex Oren <a href="mailto:alexo#bigfoot,com">alexo#bigfoot,com</a>, Mon 26 Oct 1998, 10:05 GMT
</LI>
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