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<H1>[MUD-Dev] Re: I wanna do it OO</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: I wanna do it OO</LI>
<LI><em>From</em>: Chris Gray &lt;<A HREF="mailto:cg#ami-cg,GraySage.Edmonton.AB.CA">cg#ami-cg,GraySage.Edmonton.AB.CA</A>&gt;</LI>
<LI><em>Date</em>: Sat, 24 Oct 1998 21:47:58 -0600</LI>
<LI><em>Reply-To</em>: <A HREF="mailto:mud-dev#kanga,nu">mud-dev#kanga,nu</A></LI>
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<PRE>
[James Wilson:]

 &gt;For those who like bytecode as an internal representation, I would like 
 &gt;to note that using 'interpreted objects' rather than bytecode can be quite 
 &gt;speedy. By this I mean that, for instance, a while loop can be represented
 &gt;as 
 &gt;
 &gt;struct while_exp : public expression
 &gt;{
 &gt;	virtual rep eval (vector&lt;rep&gt; &amp;stack)
 &gt;	{
 &gt;		while (_test-&gt;eval (stack))
 &gt;		_action-&gt;eval (stack);
 &gt;		return VOID_REP;
 &gt;	}
 &gt;....
 &gt;private:
 &gt;	expression *_test, *_action;
 &gt;};
 &gt;
 &gt;this sort of internal representation is also really easy to integrate
 &gt;hand-written (or automagically-generated) C/C++ code with, as opposed to
 &gt;bytecode which doesn't have such a straightforward binding.

Nod. You can also translate the above representation (which is really
just a parse tree for the program) into byte-code readily enough. This
is what I was talking about in a previous post, about being able to
'pretty-print' the parse tree into user-selectable MUD languages.
Other than having the stack be pointed to by file-static variables
instead of being passed around as in your example, this is almost
identical to the non-byte-code interpreter in my system. My struct,
from the header file:

typedef struct {
    struct Exec *wh_condition;
    struct Exec *wh_body;
} While_t;

and the code in the parse-tree interpreter for a 'while':

	case ex_while: {
	    While_t *wh;

	    wh = ex-&gt;ex_v.ex_whilePtr;
	    while (B_TRUE) {
		runExec(wh-&gt;wh_condition, &amp;leftValue, pType);
		if (leftValue.qv_integer == BOOLEAN_FALSE || Exiting) {
		    break;
		}
		runExec(wh-&gt;wh_body, pRes, pType);
		if (Aborting) {
		    Aborting = B_FALSE;
		    runError("execution timeout or abort");
		    Exiting = B_TRUE;
		}
	    }
	    *pType = TYPE_VOID;
	    break;
	}

Basically the same, except with a few of the inevitable extra details.
(Plus, its not C++ O-O stuff :-))
So, I can attest that what James is suggesting works quite well!

I did get additional speedup with bytecodes, however. I think the main
reason for this is that the above method uses a lot of function calls,
whereas a byte-code interpreter just loops internally. Also, MUD-language
function calls are a lot more expensive in my parse-tree interpreter
than in my byte-code interpreter, partly because of the need to do
general stuff to build the execution environment (like a stack frame)
for the called function.

-- 
Chris Gray     cg#ami-cg,GraySage.Edmonton.AB.CA


</PRE>

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<ul><li>Thread context:
<BLOCKQUOTE><UL>
<LI><STRONG>[MUD-Dev] Re: MUD verb handling (Was: DevMUD - thoughts.1)</STRONG>, <EM>(continued)</EM>
<ul compact>
<ul compact>
<LI><strong><A NAME="00487" HREF="msg00487.html">[MUD-Dev] Re: MUD verb handling (Was: DevMUD - thoughts.1)</A></strong>, 
Adam J. Thornton <a href="mailto:adam#phoenix,Princeton.EDU">adam#phoenix,Princeton.EDU</a>, Sun 25 Oct 1998, 15:11 GMT
</LI>
<LI><strong><A NAME="00543" HREF="msg00543.html">[MUD-Dev] Re: MUD verb handling (Was: DevMUD - thoughts.1)</A></strong>, 
Jon Leonard <a href="mailto:jleonard#divcom,slimy.com">jleonard#divcom,slimy.com</a>, Tue 27 Oct 1998, 06:57 GMT
<UL>
<LI><strong><A NAME="00549" HREF="msg00549.html">[MUD-Dev] Re: MUD verb handling (Was: DevMUD - thoughts.1)</A></strong>, 
Niklas Elmqvist <a href="mailto:d97elm#dtek,chalmers.se">d97elm#dtek,chalmers.se</a>, Tue 27 Oct 1998, 16:32 GMT
</LI>
</UL>
</LI>
</ul>
<LI><strong><A NAME="00483" HREF="msg00483.html">[MUD-Dev] Re: DevMUD - thoughts.1</A></strong>, 
James Wilson <a href="mailto:jwilson#rochester,rr.com">jwilson#rochester,rr.com</a>, Sun 25 Oct 1998, 13:47 GMT
</LI>
</ul>
</LI>
<LI><strong><A NAME="00475" HREF="msg00475.html">[MUD-Dev] Re: I wanna do it OO</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, 03:53 GMT
<LI><strong><A NAME="00472" HREF="msg00472.html">[MUD-Dev] Re: DevMUD Event Language</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, 02:37 GMT
<LI><strong><A NAME="00465" HREF="msg00465.html">[MUD-Dev] Re: PDMud, Gamora and Casbah</A></strong>, 
ApplePiMan <a href="mailto:ApplePiMan#aol,com">ApplePiMan#aol,com</a>, Sat 24 Oct 1998, 23:35 GMT
<UL>
<li>&lt;Possible follow-up(s)&gt;<br>
<LI><strong><A NAME="00471" HREF="msg00471.html">[MUD-Dev] Re: PDMud, Gamora and Casbah</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, 02:33 GMT
<UL>
<LI><strong><A NAME="00474" HREF="msg00474.html">[MUD-Dev] I wanna do it OO</A></strong>, 
James Wilson <a href="mailto:jwilson#rochester,rr.com">jwilson#rochester,rr.com</a>, Sun 25 Oct 1998, 03:14 GMT
</LI>
</UL>
</LI>
</UL>
</LI>
</UL></BLOCKQUOTE>

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