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Re: Dynamic let for lexical scope?
From: |
Michael Heerdegen |
Subject: |
Re: Dynamic let for lexical scope? |
Date: |
Wed, 13 Feb 2019 03:59:49 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) |
Hi-Angel <hiangel999@gmail.com> writes:
> I have the following function:
>
> (defun sort-lines-nocase (beg end)
> (let ((sort-fold-case t))
> (sort-lines nil beg end)))
>
> It temporarily changes sort-fold-case. Now, when compiled with
>
> ;;; -*- lexical-binding: t -*-
>
> at the top, it causes a warning "Unused lexical variable
> ‘sort-fold-case’".
The canonical answer is: add (defvar sort-fold-case) to get local
dynamical binding:
(defun sort-lines-nocase (beg end)
(defvar sort-fold-case)
(let ((sort-fold-case t))
(sort-lines nil beg end)))
In your case, I guess the problem is that `sort-lines' is autoloaded and
the variable is not yet declared when you compile (or evaluate for the
first time). So you could also add
(eval-when-compile (require 'sort))
It's a matter of taste which alternative is better or cleaner. If you
use more stuff from sort.el, it's probably better to `require' it.
Michael.