From: Barry OReilly <gundaetiapo@gmail.com>
To: help-gnu-emacs <help-gnu-emacs@gnu.org>
Subject: Re: Trouble using a lambda in the key-translation-map
Date: Thu, 19 Jul 2012 15:26:15 -0400 [thread overview]
Message-ID: <CAFM41H0-EroMdk1Gi=g6z71ruc9jKTZTCodJUbBsnbEUzpv2Rg@mail.gmail.com> (raw)
>> (defun my-translate-key (prompt) (interactive) (kbd "C-c"))
>> (define-key key-translation-map (kbd "C-e") (lambda (prompt)
>> (interactive) (kbd "C-c"))) ; Doesn't work
>> (define-key key-translation-map (kbd "C-e") 'my-translate-key) ; Works
> Look at the description of define-key -- the third argument has to be a
> SYMBOL for it to be treated as a function. Lambda doesn't return a
> function, it returns a list.
Yet this works:
(define-key global-map (kbd "C-e") (lambda () (interactive)
(message "Inside C-e's lambda")))
C-e displays the message without going to the end of the line, as expected.
I thought wherever functions are passed, a lambda could be passed
instead. The Elisp manual corroborates this in section 12.7 Anonymous
Functions: "Anonymous functions are valid wherever function names
are.". I don't see where my misunderstanding is.
I tried another thing in scratch:
(progn
(fset 'foo (lambda (prompt) (message "Inside lambda.") (kbd "C-c")))
(define-key key-translation-map (kbd "C-e") 'foo)
)
This behaves as I'd expect; I see "Inside lambda" and a translation to
C-c. Thus it would seem the type returned from the lambda form is not
the problem.
The reason I ask is because I'm trying to create a generalized way to
make key translations that either translate to another key or to
itself based on an evaluated predicate. My approach was:
(defun make-conditional-key-translation (key-from key-to translate-keys-p)
"Make a Key Translation such that if the translate-keys-p function
returns true,
key-from translates to key-to, else key-from translates to itself.
translate-keys-p
takes no args. "
(define-key key-translation-map key-from
(lambda (prompt)
(if (funcall translate-keys-p) key-to key-from)))
)
(defun my-translate-keys-p ()
"Returns whether conditional key translations should be active. See
make-conditional-key-translation function. "
(or (evil-motion-state-p) (evil-normal-state-p) (evil-visual-state-p))
)
(make-conditional-key-translation (kbd "ce") (kbd "C-e") 'my-translate-keys-p)
next reply other threads:[~2012-07-19 19:26 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-19 19:26 Barry OReilly [this message]
[not found] <mailman.5119.1342663755.855.help-gnu-emacs@gnu.org>
2012-07-19 3:45 ` Trouble using a lambda in the key-translation-map Barry Margolin
-- strict thread matches above, loose matches on Subject: below --
2012-07-18 22:45 Barry OReilly
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