From: Stefan Monnier <monnier@iro.umontreal.ca>
To: "Lennart Borgman \(gmail\)" <lennart.borgman@gmail.com>
Cc: Emacs Devel <emacs-devel@gnu.org>
Subject: Re: Why is not end-of-defun-function buffer local?
Date: Sat, 08 Dec 2007 15:16:47 -0500 [thread overview]
Message-ID: <jwvprxhdk10.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <475ADCA4.1020506@gmail.com> (Lennart Borgman's message of "Sat, 08 Dec 2007 19:04:20 +0100")
>>> It surprises me that beginning/end-of-defun-function are not always
>>> buffer local.
>>
>> Why force them to be buffer-local? When you need to set them in
>> a buffer, just do
>>
>> (set (make-local-variable 'end-of-defun-function) 'foo)
>>
>> If you think that's too long, then you may want to request a new
>> `setq-local' macro.
> setq-local would be a good idea.
> But I do not understand how you think in this case. Are not the
> variables above always meant to be buffer local?
I don't see why they should always be buffer-local. It is quite
meaningful to set this variable globally so as to get a new improved
default behavior.
> Looking at some code that is a bit older it looks like some of it uses
> make-local-variable where it is not needed since the variables in question
> are always buffer local. From that I draw the conclusion that the code in
> Emacs uses make-variable-buffer-local more often now. Is not that the case?
make-variable-buffer-local has the following downsides:
1 - it cannot be reverted.
2 - it may be done too late.
3 - when you see `setq' it's not obvious that the setting is buffer-local
unless you remember seeing the call to make-variable-buffer-local.
The second problem may also explain what you're seeing: some code may
set a variable before the make-variable-buffer-local gets run.
It's actually "common" to introduce bugs this way, because people see
"this is automatically buffer-local" in the C-h v info, so they just use
`setq' without realizing that the setq may occur before the package
gets loaded.
make-variable-buffer-local is not evil, but make-local-variable is much
tamer and more explicit, and it works just as well in most cases.
Stefan
next prev parent reply other threads:[~2007-12-08 20:16 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-08 1:02 Why is not end-of-defun-function buffer local? Lennart Borgman (gmail)
2007-12-08 2:18 ` Stefan Monnier
2007-12-08 18:04 ` Lennart Borgman (gmail)
2007-12-08 20:16 ` Stefan Monnier [this message]
2007-12-09 1:45 ` Lennart Borgman (gmail)
2007-12-09 2:45 ` Stefan Monnier
2007-12-09 3:04 ` Lennart Borgman (gmail)
2007-12-09 13:02 ` martin rudalics
2007-12-10 5:13 ` Stefan Monnier
2007-12-11 12:53 ` martin rudalics
2007-12-11 14:58 ` Stefan Monnier
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