From: "Pascal J. Bourguignon" <pjb@informatimago.com>
To: help-gnu-emacs@gnu.org
Subject: Re: Real-life examples of lexical binding in Emacs Lisp
Date: Sun, 14 Jun 2015 23:44:45 +0200 [thread overview]
Message-ID: <878ubmvub6.fsf@kuiper.lan.informatimago.com> (raw)
In-Reply-To: jwveglekqlm.fsf-monnier+gnu.emacs.help@gnu.org
Stefan Monnier <monnier@iro.umontreal.ca> writes:
>>> However, I would argue that for global variables, lexical binding would
>>> be useful too, even by default.
>
> I'm not sure what that means. But you can set a global value to
> a variable without declaring it as dynamically scoped:
>
> (setq my-lex-var 3)
Wrong.
Having a file lex.el:
------------------------------------------------------------------------
;; -*- mode:emacs-lisp; lexical-binding:nil -*-
(setq lexical? 33)
(defun f ()
lexical?)
(defun g ()
(let ((lexical? 42))
(f)))
(print (g))
------------------------------------------------------------------------
Then M-x load-file RET lex.el RET writes 42 in *Message* which shows
that lexical? IS a dynamic variable! If it was lexical, we would get
33, because the lexical scope of the closure f is the global scope,
where lexical? as been bound to 33, not the local dynamic scope of the
function g when the variable lexical? is bound to 42.
> Inside Emacs we also have a few global vars (e.g. `pi' and `argv') which
> we would want to declare with something like defvar for various reasons
> (providing a docstring, recording where is the declaration, etc...) yet
> we don't want them to be dynamically scoped.
>
> For `pi' we just used `setq', and for `argv' we used defvar followed by
> an ugly hack called internal-make-var-non-special.
>
>
> Stefan
--
__Pascal Bourguignon__ http://www.informatimago.com/
“The factory of the future will have only two employees, a man and a
dog. The man will be there to feed the dog. The dog will be there to
keep the man from touching the equipment.” -- Carl Bass CEO Autodesk
next prev parent reply other threads:[~2015-06-14 21:44 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-29 8:28 Real-life examples of lexical binding in Emacs Lisp Marcin Borkowski
2015-05-30 8:28 ` Tassilo Horn
2015-06-14 10:52 ` Marcin Borkowski
[not found] ` <mailman.4976.1434279182.904.help-gnu-emacs@gnu.org>
2015-06-14 11:31 ` Pascal J. Bourguignon
2015-06-16 23:48 ` Jim Diamond
2015-06-17 0:06 ` Emanuel Berg
2015-06-17 6:23 ` Andreas Röhler
[not found] ` <mailman.5136.1434522217.904.help-gnu-emacs@gnu.org>
2015-06-17 10:49 ` Pascal J. Bourguignon
2015-06-17 10:53 ` Pascal J. Bourguignon
2015-06-17 14:42 ` Stefan Monnier
2015-06-17 16:19 ` Andreas Röhler
2015-06-17 19:30 ` Tassilo Horn
[not found] ` <mailman.5171.1434557990.904.help-gnu-emacs@gnu.org>
2015-06-17 17:12 ` Stefan Monnier
2015-06-17 20:22 ` Emanuel Berg
2015-06-17 22:13 ` Pascal J. Bourguignon
2015-06-17 23:46 ` Emanuel Berg
2015-06-18 14:57 ` Udyant Wig
2015-06-18 15:47 ` Emanuel Berg
2015-06-19 13:49 ` Udyant Wig
2015-06-19 17:41 ` acronymania (was: Re: Real-life examples of lexical binding in Emacs Lisp) Emanuel Berg
2015-06-19 17:53 ` Rusi
2015-06-17 20:33 ` Real-life examples of lexical binding in Emacs Lisp Emanuel Berg
2015-06-17 22:07 ` Robert Thorpe
2015-06-17 22:17 ` Pascal J. Bourguignon
2015-06-17 0:43 ` Pascal J. Bourguignon
2015-06-17 16:02 ` Phillip Lord
[not found] ` <mailman.5167.1434556959.904.help-gnu-emacs@gnu.org>
2015-06-23 23:49 ` Jim Diamond
[not found] ` <mailman.3950.1432974543.904.help-gnu-emacs@gnu.org>
2015-05-30 12:59 ` Pascal J. Bourguignon
2015-06-14 10:55 ` Marcin Borkowski
[not found] ` <mailman.4977.1434279342.904.help-gnu-emacs@gnu.org>
2015-06-14 20:04 ` Stefan Monnier
2015-06-14 21:44 ` Pascal J. Bourguignon [this message]
2015-06-14 21:49 ` Pascal J. Bourguignon
[not found] <mailman.3883.1432888152.904.help-gnu-emacs@gnu.org>
2015-05-29 9:30 ` Joost Kremers
2015-05-29 11:12 ` Andreas Röhler
2015-05-29 12:13 ` Dmitry Gutov
2015-05-29 16:21 ` Phillip Lord
2015-05-29 16:50 ` Yuri Khan
2015-05-29 12:28 ` Pascal J. Bourguignon
2015-05-29 17:16 ` Andreas Röhler
2015-05-29 18:43 ` Emanuel Berg
2015-05-30 5:49 ` Rusi
2015-05-30 12:50 ` Pascal J. Bourguignon
2015-05-30 15:23 ` Rusi
2015-05-30 15:50 ` Pascal J. Bourguignon
2015-05-30 16:21 ` Rusi
2015-05-30 16:03 ` Emanuel Berg
2015-05-30 16:32 ` Rusi
2015-05-30 16:54 ` Pascal J. Bourguignon
2015-05-30 17:10 ` Rusi
2015-05-30 19:12 ` Pascal J. Bourguignon
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