GNU bug report logs - #9469
buffer-local variables seem to remember previous values

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Message #54 received at 9469 <at> debbugs.gnu.org (full text, mbox):

From: "Drew Adams" <drew.adams <at> oracle.com>
To: "'Andreas Schwab'" <schwab <at> linux-m68k.org>, "'Le Wang'" <l26wang <at> gmail.com>
Cc: 'Lars Magne Ingebrigtsen' <larsi <at> gnus.org>, 9469 <at> debbugs.gnu.org
Subject: RE: bug#9469: buffer-local variables seem to remember previous values
Date: Mon, 12 Sep 2011 07:30:24 -0700

> > My point is that the manual would be more helpful to someone in my
> > position if it had an example saying don't modify quoted 
> > objects, and why.
> 
> This has nothing at all to do with quoting.  Don't use destructive
> functions if you don't know what you are doing.

Everything that people have said in the thread is true.  That doesn't mean that
we can't help users more in this regard.

What could perhaps be made clearer in the manual - and perhaps in the Lisp Intro
manual (e.g., with pedagogic examples), is the role of the Lisp reader in
creating list structure, symbols, etc.  It is ignorance of or forgetting about
this feature of Lisp that confuses users (esp. newbies) when it comes to `quote'
etc.

Explanation of Lisp reading is far removed in the manual from the description of
`quote' (and they are not directly related, so there is nothing wrong with
this).  It might help to (a) develop the reader-creates-objects subject in the
Lisp Intro manual and (b) put a reminder about this in the section about
`quote', with a caveat about modifying etc.

In sum, it's not about whether you or the manual or Le is right or wrong.  It's
about helping users.  And yes, this is a potential point of confusion.  The
consequences of the Lisp reader creating things are not necessarily obvious to
newbies.

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