Path: utzoo!utgpu!water!watmath!clyde!ima!think!barmar
From: barmar@think.COM (Barry Margolin)
Newsgroups: comp.lang.lisp
Subject: Re: Disabling colons in CommonLisp
Keywords: help!
Message-ID: <24747@think.UUCP>
Date: 1 Aug 88 19:02:13 GMT
References: <2694@mind.UUCP>
Sender: usenet@think.UUCP
Reply-To: barmar@kulla.think.com.UUCP (Barry Margolin)
Organization: Thinking Machines Corporation, Cambridge, MA
Lines: 28

In article <2694@mind.UUCP> romero@mind.UUCP (Antonio Romero) writes:
>So I need a solution which would allow tokens to end in colons, without
>breaking the other special interpretations associated with colons.
>Ideally this would be possible within the CommonLisp standard, so as to be
>portable, but I'll settle for a non-portable solution if I have to.
>Has anyone out there solved this one already?

It will have to be non-portable, as there is no way to write what
colon does within Common Lisp.  The problem is that the handler for
the colon character needs to back up the parser, and the Common Lisp
reader macro facility doesn't provide that functionality; reader
macros can only look ahead.  Colon has to be built in to the reader so
that it can do this.

Couldn't you write an editor macro or sed script to go through your
production source files and put a backslash before the colons?

If you don't use colons for their Common Lisp meaning in the same
files as your productions then you could bind *READTABLE* to a
readtable that has colon defined as a constituent character while you
load the productions.  When you are loading Lisp source files you
would use the regular readtable.

Barry Margolin
Thinking Machines Corp.

barmar@think.com
{uunet,harvard}!think!barmar