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Re: Using variable names in a macro
From: |
Narendra Joshi |
Subject: |
Re: Using variable names in a macro |
Date: |
Sun, 10 Dec 2017 20:12:18 +0530 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.0.90 (gnu/linux) |
Michael Heerdegen <michael_heerdegen@web.de> writes:
> Narendra Joshi <narendraj9@gmail.com> writes:
>
>> ```
>> (defmacro do-when-idle (f g interval)
>> "Call F when idle for INTERVAL seconds and then G when there is activity."
>> `(progn
>> (defun ,(intern (concat "do-when-idle-"
>> (sha1 (format "%s-%s" f g)))) ()
>> (funcall ,g)
>> (remove-hook 'post-command-hook
>> #',(intern (concat "do-when-idle-"
>> (sha1 (format "%s-%s" f g)))))
>> (run-with-idle-timer ,interval
>> nil
>> (lambda ()
>> (funcall ,f)
>> (add-hook 'post-command-hook
>> #',(intern (concat "do-when-idle-"
>> (sha1 (format
>> "%s-%s" f g))))))))
>> (run-with-idle-timer ,interval
>> nil
>> (lambda ()
>> (funcall ,f)
>> (add-hook 'post-command-hook
>> #',(intern (concat "do-when-idle-"
>> (sha1 (format
>> "%s-%s" f g)))))))))
>> ```
>
> Hmm, with some trivial simplifications of the list building, this could
> look like:
>
> #+begin_src emacs-lisp
> (defmacro do-when-idle (f g interval)
> "Call F when idle for INTERVAL seconds and then G when there is activity."
> (let* ((name (intern (concat "do-when-idle-"
> (sha1 (format "%s-%s" f g)))))
> (run-idle-timer-form `(run-with-idle-timer
> ,interval
> nil
> (lambda ()
> (funcall ,f)
> (add-hook 'post-command-hook #',name)))))
> `(progn
> (defun ,name ()
> (funcall ,g)
> (remove-hook 'post-command-hook #',name)
> ,run-idle-timer-form)
> ,run-idle-timer-form)))
> #+end_src
This is a lot cleaner. Thanks! :)
> It would be better, though, to replace the run-idle-timer-form from with
> a lambda, to avoid the code duplication.
>
> Actually, `do-when-idle' doesn't even have to be a macro. You can make
> it a defun when you define the NAME with defalias. Bind it to a closure
> so that you can refer to all of the stuff with variables bound around
> it.
Can you share an example please? :)
--
Narendra Joshi