Path: news.daimi.aau.dk!news.uni-c.dk!sunic!ugle.unit.no!nac.no!ifi.uio.no!nntp!alfh
From: alfh@byleist.ifi.uio.no (Alf-Ivar Holm)
Newsgroups: comp.lang.beta
Subject: Re: Recursive, double INNER
Date: 14 Feb 1995 12:29:44 GMT
Organization: Dept. of Informatics, University of Oslo, Norway
Lines: 51
Message-ID: <ALFH.95Feb14132944@byleist.ifi.uio.no>
References: <ALFH.95Feb6204201@byleist.ifi.uio.no> <3hntel$17j@belfort.daimi.aau.dk>
NNTP-Posting-Host: byleist.ifi.uio.no
In-reply-to: olevi@daimi.aau.dk's message of 13 Feb 1995 15:21:57 GMT
CC: 

In article <3hntel$17j@belfort.daimi.aau.dk> olevi@daimi.aau.dk (Ole Villumsen) writes:

> I know (Jens Cornelius Olsen) has already followed up to this question.
> I think I have a different solution that I personally like better.
> I avoid the use of pattern references (##'s). Instead I use another block
> level:
> 
> forAllThings:
>   (# before:< ...
>      after:< ...
>      recursiveForAll:<
>        (# do before; ... &recursiveForAll; ... after; #);
>   do &recursiveForAll;
>   #);
> 
> forAllDingbats: forAllThings
>   (# before::< (# ... #);
>      after::< (# ... #);
>   #);
> 
> Does this solve your problem?

It does solve the problem, and it looks prettier, but it may introduce
another complication because of the new block level:

If there are some variables in forAllThings that is accessible to
before and after, let us say some "current" pointer that is set before
"before".  This variable is updated in recursiveForAll, but is
declared in forAllThings, to make it accessible to before and after.
Since this is a global variable to recursiveForAll, it have to be
reset before the "after" call, since some recursive call to
recursiveForAll have changed current. 

Something like:

   forAllThings:
     (# before:< ...
 	after:< ...
 	current: someObject;
	recursiveForAll:
        (# do
           ... foo[] -> current[]; before;
           ... &recursiveForAll; ...
           foo[] -> current[]; after; 
          #);
     do &recursiveForAll;
     #);

It does solve the problem, but you have to be careful!

	Affi