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Re: ~`symbol-function' to get code as list even when byte-compiled?
From: |
Barry Margolin |
Subject: |
Re: ~`symbol-function' to get code as list even when byte-compiled? |
Date: |
Sun, 24 May 2015 22:58:18 -0400 |
User-agent: |
MT-NewsWatcher/3.5.3b3 (Intel Mac OS X) |
In article <877frxid14.fsf@debian.uxu>,
Emanuel Berg <embe8573@student.uu.se> wrote:
> (re-search-forward "^Question")
>
> Here is some interesting code. What's interesting is:
> when this code executes, it changes itself, i.e.
> the code changes the code!
>
> But it isn't a macro which is a program that produces
> a new program based on its own logic and non-evaluated
> input data.
>
> On the contrary, here we deal all with ordinary
> functions (defuns) where one changes the other.
> Does that always happen? No - only when it is needed!
>
> See the entire code here [1]. Go there if you want to
> see this in execution as it probably is based on some
> other functions as well. The below code is for display
> purposes ONLY!
>
> Question: this is all working thanks to
> `symbol-function' which is used to get the code of the
> function as data, so it can be examined and
> manipulated. However, if I byte-compile the code
> (which I always do), `symbol-function' doesn't return
> a lambda function which is also a list, but instead
> just a function #[...] which isn't a list. So then it
> doesn't work!
>
> I was able to do a workaround with `load-file' in
> .emacs to get all the functions in the file in
> evaluated form. But, can I do that specifically for
> a named function, *or*, can I extract the code in list
> format somehow even if compiled?
You can probably prevent it from being compiled, maybe something like:
(setf (symbol-function 'number-one-jump)
'(lambda (&optional not-used) ...))
But can't you do something equivalent by using advice instead of
self-modifying code?
>
> (symbol-function jump)
>
> (defun enable-jump (jump)
> (add-hook 'w3m-display-hook jump)
> (let*((code (symbol-function jump))
> (remove-code `(remove-hook 'w3m-display-hook (quote ,jump)))
> (remove-code-index 2)
> (current-code (nth remove-code-index code)) )
> (unless (equal current-code remove-code)
> (push remove-code (nthcdr remove-code-index code)) )))
>
> (defun web-search ()
> (interactive)
> (let ((search (get-search-string "Google")))
> (unless (empty-string-p search)
> (w3m-new-tab (format "Google: %s" search))
> (w3m-search w3m-search-default-engine search) ))
> (enable-jump 'number-one-jump) )
>
> (defun number-one-jump (&optional not-used) ; Google, Youtube
> (when (re-search-forward "^ 1." (point-max) t)
> (recenter-top-bottom 0)
> (w3m-next-anchor) ))
>
> [1] http://user.it.uu.se/~embe8573/conf/emacs-init/w3m/w3m-unisearch.el
--
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
- ~`symbol-function' to get code as list even when byte-compiled?, Emanuel Berg, 2015/05/24
- Re: ~`symbol-function' to get code as list even when byte-compiled?,
Barry Margolin <=
- Re: ~`symbol-function' to get code as list even when byte-compiled?, Pascal J. Bourguignon, 2015/05/24
- Re: ~`symbol-function' to get code as list even when byte-compiled?, Emanuel Berg, 2015/05/25
- Re: ~`symbol-function' to get code as list even when byte-compiled?, Pascal J. Bourguignon, 2015/05/25
- Message not available
- Re: ~`symbol-function' to get code as list even when byte-compiled?, Emanuel Berg, 2015/05/25
- Re: ~`symbol-function' to get code as list even when byte-compiled?, Pascal J. Bourguignon, 2015/05/25
- Message not available
- Re: ~`symbol-function' to get code as list even when byte-compiled?, Emanuel Berg, 2015/05/25
- Re: ~`symbol-function' to get code as list even when byte-compiled?, Emanuel Berg, 2015/05/25
- Re: ~`symbol-function' to get code as list even when byte-compiled?, Stefan Monnier, 2015/05/26