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Re: With lexical-binding t, how do I bind an external symbol dynamicall?
From: |
Alan Mackenzie |
Subject: |
Re: With lexical-binding t, how do I bind an external symbol dynamicall? |
Date: |
Sat, 29 Aug 2015 18:07:05 +0000 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
Hello, Philipp.
On Sat, Aug 29, 2015 at 05:30:20PM +0000, Philipp Stephani wrote:
> Alan Mackenzie <address@hidden> schrieb am Sa., 29. Aug. 2015 um 18:34 Uhr:
> > Hello, Emacs!
> > In some Elisp with no knowledge of the variable `some-flag', which will
> > be defined elsewhere, I want to write
> > (let (some-flag) ....)
> > to bind `some-flag' dynamically. The byte-compiler give me the warning:
> > Unused lexical variable `some-flag'
> > . Somehow, I need to tell the byte-compiler that `some-flag' will be an
> > external dynamic variable. How do I do this?
> Use (defvar some-flag) before using some-flag. That will do nothing except
> marking some-flag as special (dynamic).
Ah! It's obvious, isn't it? ;-) Thank you very much indeed! I've now
restored the lexical-binding to the pertinent file.el
> > I've had a look around the "Variables" page, and its sub-pages, in the
> > elisp manual, yet didn't find any instructions on how to get round this
> > problem. Where in the manual is it described?
> It's mentioned in 16.6 Compiler Errors, but without mentioning dynamic
> binding. I discovered the behavior by looking at the Emacs source code; but
> this should be stated more prominently in the Elisp manual because it can
> lead to subtle errors if the warning is ignored or silenced.
Yes. I think a bug report is in order.
--
Alan Mackenzie (Nuremberg, Germany).