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bug#35231: 26.1; Redefine `read-command' behavior for empty input and DE
From: |
Lars Ingebrigtsen |
Subject: |
bug#35231: 26.1; Redefine `read-command' behavior for empty input and DEFAULT not a command name |
Date: |
Tue, 09 Jul 2019 17:39:52 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) |
Drew Adams <drew.adams@oracle.com> writes:
> This is a followup to bug #35222 (and thanks for fixing that doc bug).
>
> As discussed in #35222, the current C-code definition of `read-command'
> seems not so desirable, when it comes to DEFAULT = nil or "".
>
> The behavior in that case is to return an uninterned symbol whose name
> is empty, which has the read/print syntax `##'.
>
> This is _not_ a symbol whose function definition is `commandp'. There
> is nothing about this symbol that qualifies for consideration as a
> command. It seems wrong (a bug) for `read-command' to ever return a
> symbol whose function definition is `commandp'.
That is, indeed, pretty odd. The function isn't used a lot in Emacs:
./lisp/subr.el1088: (read-command (format "Set key %s to command: "
./lisp/edmacro.el118: (setq cmd (read-command "Name of keyboard macro to
edit: "))
./lisp/emulation/edt.el1130: (setq edt-function (read-command "Enter command
name: "))
./lisp/info.el4526: (read-command "Find documentation for command: ")))
./lisp/strokes.el448: (read-command "Command to map stroke to: ")))
But some of them expect this behaviour:
(setq cmd (read-command "Name of keyboard macro to edit: "))
(if (string-equal cmd "")
(error "No command name given"))
(setq edt-function (read-command "Enter command name: "))
(if (string-equal "" edt-function)
(message "Key not defined")
So changing the behaviour is probably not a good idea -- there may be
out-of-tree usages. So I think we'll have to live with it, and I'm
closing this bug report.
--
(domestic pets only, the antidote for overdose, milk.)
bloggy blog: http://lars.ingebrigtsen.no
- bug#35231: 26.1; Redefine `read-command' behavior for empty input and DEFAULT not a command name,
Lars Ingebrigtsen <=