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Path: utzoo!linus!decvax!harpo!seismo!rlgvax!cvl!umcp-cs!chris
From: chris@umcp-cs.UUCP
Newsgroups: net.emacs
Subject: Re: bug in arg passing
Message-ID: <1794@umcp-cs.UUCP>
Date: Sat, 13-Aug-83 02:50:26 EDT
Article-I.D.: umcp-cs.1794
Posted: Sat Aug 13 02:50:26 1983
Date-Received: Sat, 13-Aug-83 19:14:20 EDT
References: <866@pur-phy.UUCP>
Organization: Univ. of Maryland, Computer Science Dept.
Lines: 39

That's not a bug, it's a feature!  :-)

The problem is that everything is a FEXPR (if I have my lisp terminology
correct):

(defun (foo1 z
	(setq z 10)
	(foo2 z)))
(defun (foo2 z
	(message "z = " z)))

exhibits the same problem.  ("z = 0")

The fix I have decided on is to write such functions as

(defun
    (foo1 arg1
	(setq arg1 (arg 1))
	(progn max-attempts i
	    (setq max-attempts arg1)
	    .
	    .
	    .

In other words, all arguments will put into be "arg1", "arg2", . . .
up until the actual code itself, which will be inside a progn which
declares the real variable names, and then moves the "arg"s to the
real variables.

This is essentially doing by hand what a real lisp system would do
for you (evaluating arguments before binding new variables).

				- Chris

PS You can even write recursive MLisp code this way!  (shudder)
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci
UUCP:	{seismo,allegra,brl-bmd}!umcp-cs!chris
CSNet:	chris@umcp-cs		ARPA:	chris.umcp-cs@UDel-Relay