From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Juanma Barranquero <lekktu@gmail.com>
Cc: emacs-devel@gnu.org
Subject: Re: Lexical binding
Date: Mon, 04 Apr 2011 17:44:30 -0400 [thread overview]
Message-ID: <jwv7hb91yud.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <BANLkTinvkFgKBjLMPE9-xNdzh5B2fX49ow@mail.gmail.com> (Juanma Barranquero's message of "Mon, 4 Apr 2011 18:04:34 +0200")
>> Check the `dolist' macro, it has a FIXME for that.
> OK, fair enough. Sorry for the noise.
> Is this one also documented (or has a logical explanation that I'm
> again missing)?
No, it's not documented tho it's the same underlying problem:
> ;; test.el -*- lexical-binding: t -*-
> (condition-case test
> (ignore)
> (quit test)
> (error test))
> ;; end
> No error. Now, if you remove `test' in either handler:
Right. Internally, the condition-case above is turned into
(condition-case :fun-body
(lambda () (ignore))
(quit (lambda (test) test))
(error (lambda (test) test)))
I.e. the underlying problem (shared with dolist and some pcase
situations as well) is that one binding occurrence of a variable (above,
`test') is turned into 2 or more, so you can get warnings about an
unused variable because some of the its binders aren't used, but since
it really corresponds to a single binder in the source code the
programmer can't really fix it, hence the warning is an annoyance.
I'm not sure yet how best to solve the issue. The main problem is
that this warning is important to help convert programs from dynamic to
lexical scoping, so it's an important tool and hence shouldn't be silenced
too lightheartedly.
Stefan
next prev parent reply other threads:[~2011-04-04 21:44 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-01 17:32 Lexical binding Stefan Monnier
2011-04-01 19:12 ` David De La Harpe Golden
2011-04-01 19:46 ` Eli Zaretskii
2011-04-04 16:05 ` Stefan Monnier
2011-04-01 20:04 ` Daniel Colascione
2011-04-01 20:39 ` cedet-bzr build failure (was : Lexical binding) Darren Hoo
2011-04-01 21:21 ` David Engster
2011-04-01 22:26 ` Darren Hoo
2011-04-02 12:40 ` David Engster
2011-04-02 13:42 ` Eric M. Ludlam
2011-04-02 18:22 ` cedet-bzr build failure David Engster
2011-04-02 18:29 ` cedet-bzr build failure (was : Lexical binding) Darren Hoo
2011-04-01 20:42 ` Lexical binding Eli Zaretskii
2011-04-01 22:13 ` Juanma Barranquero
2011-04-02 2:33 ` Juanma Barranquero
2011-04-02 3:36 ` Juanma Barranquero
2011-04-02 18:38 ` Stefan Monnier
2011-04-04 16:04 ` Juanma Barranquero
2011-04-04 21:44 ` Stefan Monnier [this message]
2011-04-04 21:56 ` Juanma Barranquero
2011-04-04 22:03 ` David Kastrup
2011-04-04 22:34 ` Stefan Monnier
2011-04-02 18:38 ` Stefan Monnier
2011-04-02 18:50 ` Juanma Barranquero
2011-04-02 18:57 ` Juanma Barranquero
2011-04-03 12:05 ` Christian Ohler
2011-04-03 12:26 ` Juanma Barranquero
2011-04-03 23:32 ` Christian Ohler
2011-04-04 0:12 ` Juanma Barranquero
2011-04-04 16:22 ` Stefan Monnier
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