GNU bug report logs - #6591
24.0.50; incorrect doc for `catch'

Previous Next

Full log

Message #29 received at 6591 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Drew Adams <drew.adams <at> oracle.com>
Cc: 6591 <at> debbugs.gnu.org
Subject: Re: bug#6591: 24.0.50; incorrect doc for `catch'
Date: Sat, 10 Jul 2010 18:55:18 +0300

> From: "Drew Adams" <drew.adams <at> oracle.com>
> Cc: <6591 <at> debbugs.gnu.org>
> Date: Sat, 10 Jul 2010 08:44:47 -0700
> 
> > > Ah! Then the syntax should be (catch TAG . BODY) or similar.
> >                                           ^^^
> > Why the period?
> 
> Same reason as your special `BODY...' syntax.  It means _splice in_ the list
> BODY.  Or if you like, it means that BODY is the cdr of the sexp as a list.  Or
> if you like, it is equivalent to ,@BODY in backquote syntax.
> 
> You cannot write just (catch TAG BODY).  There must be some indication (`.',
> `...' or other) to distinguish normal substitution for a placeholder from
> splicing substitution for a placeholder.  Substitution for TAG is treated
> differently from substitution for BODY.
> 
> But are you just playing/kidding here? or arguing?  What's the point?  I'm sure
> that you understand the syntax (A . B) in Lisp and in our docs.  I assume you
> are trying to make some point, but I fail to see it.

I was thinking of modifying the docs to say `catch TAG BODY' and
explaining in the text that BODY can be one or more forms.

The problem with the period is that it could be misunderstood to mean
that a period must be present in the catch form at this point, which
is false.

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.