From: Pedro Andres Aranda Gutierrez <paaguti@gmail.com>
To: Tim Cross <theophilusx@gmail.com>
Cc: Phil Sainty <psainty@orcon.net.nz>, Eli Zaretskii <eliz@gnu.org>,
emacs-devel@gnu.org
Subject: Re: PATCH: Explicitly show how let works on global-variables
Date: Thu, 6 Oct 2022 11:00:45 +0200 [thread overview]
Message-ID: <CAO48Bk-Hk7WaV8=p4amSwcwjPgS6ePswMCgXcp_yYOOrst3vbw@mail.gmail.com> (raw)
In-Reply-To: <CAO48Bk9NrBYZP_88m8Q8MnR=P-HG+xEavHPbR4jEQCrzoYCN8g@mail.gmail.com>
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So, can someone more informed than myself provide an informed patch
Thanks, /PA
On Wed, 5 Oct 2022 at 07:28, Pedro Andres Aranda Gutierrez <
paaguti@gmail.com> wrote:
> Even more so in the light of lexical binding. I'm trying to introduce
> people to Emacs and the easier to understand and use as a source of
> inspiration this manual is, the more probable it is that people actually
> switch to Emacs. (Or at least this is what I have seen after using it for 7
> years as an option in the practical assignments)
>
> /PA
>
> On Wed, 5 Oct 2022 at 00:22, Tim Cross <theophilusx@gmail.com> wrote:
>
>>
>> Phil Sainty <psainty@orcon.net.nz> writes:
>>
>> > On 2022-10-04 21:09, Pedro Andres Aranda Gutierrez wrote:
>> >> I understood as local variable a 'value that was stored in the
>> >> function's stack' to be used in the scope of the let. That implied
>> >> (once again in my understanding) that the global system-time-locale
>> >> would not be affected and hence format-time-string would not see the
>> >> change in the value within the let.
>> >
>> > Since the addition of lexical binding to Emacs Lisp in Emacs 24.1,
>> > both results are possible depending on whether you are dealing with
>> > a dynamic or a lexical variable.
>> >
>> > I.e. given:
>> >
>> > (defun myfunc () foo)
>> > (let ((foo 'bar)) (myfunc))
>> >
>> > If foo is a dynamic variable then the let form will return 'bar.
>> >
>> > If foo is a lexical variable, then you'd get this error:
>> > "let: Symbol’s value as variable is void: foo".
>> >
>> > Eli quoted the manual:
>> >
>> > Local variables created by a ‘let’ expression retain their value
>> > _only_ within the ‘let’ expression itself (and within expressions
>> called
>> > within the ‘let’ expression); the local variables have no effect
>> outside
>> > the ‘let’ expression.
>> >
>> > That "(and within expressions called within the ‘let’ expression)" is
>> > pretty ambiguous wrt dynamic vs lexical binding, and a few lines later
>> > it comments very briefly on this:
>> >
>> > in Emacs Lisp, the default scoping is dynamic, not lexical.
>> > (The non-default lexical binding is not discussed in this manual.)
>> >
>> > Which keeps the rest of the text accurate, yet in an almost-entirely
>> > unexplained manner.
>> >
>> > I suggest that at this point it has become pretty necessary for lexical
>> > binding to be discussed in this manual...
>> >
>> > * The *scratch* buffer, in which users will perform many if not most of
>> > their experiments, now uses lexical binding by default.
>> >
>> > * If enabled, auto-insert-mode adds lexical-binding: t to new elisp
>> files
>> > by default.
>> >
>> > * IIRC most elisp files in Emacs core are now using lexical binding.
>> >
>> > * The emacs-lisp-mode mode-name treats dynamic binding as a warning.
>> >
>> > So while it's as true as ever that dynamic binding is the default, the
>> > fact that so many things nowadays default to *enabling* lexical binding
>> > really blurs this line, to the point where I think it's unreasonable to
>> > avoid discussing lexical binding in the introduction to emacs lisp, as
>> > the user will almost unavoidably be exposed to it.
>> >
>> > I think examples would be hugely helpful in explaining the difference
>> > between the two types of binding.
>> >
>>
>> +1. I think this has become quite important.
>>
>
>
> --
> Fragen sind nicht da um beantwortet zu werden,
> Fragen sind da um gestellt zu werden
> Georg Kreisler
>
> Headaches with a Juju log:
> unit-basic-16: 09:17:36 WARNING juju.worker.uniter.operation we should run
> a leader-deposed hook here, but we can't yet
>
>
--
Fragen sind nicht da um beantwortet zu werden,
Fragen sind da um gestellt zu werden
Georg Kreisler
Headaches with a Juju log:
unit-basic-16: 09:17:36 WARNING juju.worker.uniter.operation we should run
a leader-deposed hook here, but we can't yet
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next prev parent reply other threads:[~2022-10-06 9:00 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-04 6:46 PATCH: Explicitly show how let works on global-variables Pedro Andres Aranda Gutierrez
2022-10-04 7:52 ` Eli Zaretskii
2022-10-04 8:09 ` Pedro Andres Aranda Gutierrez
2022-10-04 11:36 ` Phil Sainty
2022-10-04 13:43 ` Stefan Monnier
2022-10-04 22:22 ` Tim Cross
2022-10-05 5:28 ` Pedro Andres Aranda Gutierrez
2022-10-06 9:00 ` Pedro Andres Aranda Gutierrez [this message]
2022-10-06 19:34 ` Emanuel Berg
2022-10-04 17:39 ` Richard Stallman
2022-10-04 7:59 ` tomas
2022-10-04 11:56 ` Phil Sainty
2022-10-04 13:48 ` Stefan Monnier
2022-10-05 21:31 ` Richard Stallman
2022-10-04 15:00 ` [External] : " Drew Adams
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