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Re: Dynamically constructing advice behaves strangely
From: |
Marcin Borkowski |
Subject: |
Re: Dynamically constructing advice behaves strangely |
Date: |
Sun, 14 Feb 2016 21:58:46 +0100 |
User-agent: |
mu4e 0.9.13; emacs 25.1.50.2 |
On 2016-02-14, at 16:44, Michael Heerdegen <michael_heerdegen@web.de> wrote:
> Marcin Borkowski <mbork@mbork.pl> writes:
>
>> (defun add-constructed-advice (fun)
>> "Add a constructed advice to function foo."
>> (let* ((fun-name (symbol-name fun))
>> (length-sym
>> (make-symbol (concat "length-of-" fun-name)))
>> (piece-of-advice-sym
>> (make-symbol (concat "advice-for-" fun-name)))
>> (piece-of-advice (lambda (orig-fun &rest args)
>> (apply orig-fun args)
>> (message "This function's name had length %s."
>> (symbol-value length-sym)))))
>
> Also, `length-sym' doesn't have to be an uninterned symbol here. You
> use lexical-binding anyway (by referring to the value of the (interned!)
> symbol named "length-sym". You don't even have to use a symbol with a
> unique name. Just use a simple (lexical) variable for the length,
> e.g. `advice-length', and
>
> (message "This function's name had length %s." advice-length)
>
> etc. (your piece of advice is a closure!).
I know, and in fact I'm making use of lexical binding in my "real"
code. This was just a trimmed-down version for the sake of asking here.
> Michael.
Best,
--
Marcin Borkowski
http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski
Faculty of Mathematics and Computer Science
Adam Mickiewicz University