Path: utzoo!utgpu!water!watmath!clyde!rutgers!umd5!purdue!gatech!bloom-beacon!ptt.lcs.mit.edu!markl
From: markl@PTT.LCS.MIT.EDU
Newsgroups: comp.emacs
Subject: Re: Need help w/ Gnu auto-mode-alist
Message-ID: <8802161514.AA04381@PTT.LCS.MIT.EDU>
Date: 16 Feb 88 15:14:50 GMT
Sender: daemon@bloom-beacon.MIT.EDU
Reply-To: markl@PTT.LCS.MIT.EDU
Lines: 41
To: nntp-poster@PTT.LCS.MIT.EDU
Repository: PTT
Originating-Client: thyme


   From: warsaw@cme-durer.ARPA (Barry A. Warsaw)
   Date: 12 Feb 88 21:37:43 GMT
   Organization: National Bureau of Standards

   (setq auto-mode-alist
	   (append
		   '(("^/tmp/\\(post\\|fol\\)a[0-9]*" . text-mode)
		   auto-mode-alist)))

   My question is: what's the difference between using append and cons?
   Is there a difference?  I think I used a template I saw in one of
   gnu's .el files

From the documentation:

----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- 

append:
Concatenate arguments and make the result a list.
The result is a list whose elements are the elements of all the arguments.
Each argument may be a list, vector or string.

cons:
Create a new cons, give it CAR and CDR as components, and return it.

----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- 

One immediately obvious difference is therefore that (append nil '(a))
gives '(a) whereas (cons nil '(a)) gives '(nil a).  


markl

Internet: markl@ptt.lcs.mit.edu

Mark L. Lambert
MIT Laboratory for Computer Science
Distributed Systems Group

----------