Local elisp library files and variable corruption

Local elisp library files and variable corruption

[Live System User]

Hi,

        I'm trying to track down a possible problem with using
        local copies of elisp library files and variable
        corruption.

        I know that some Emacs libraries are dumped into Emacs
        so this may not be a problem with usage but only with its
        interaction with functions like `describe-variable'.

        Here's an example:

0. Create a .emacs file with the contents:

(add-to-list 'load-path "~/.emacs.d/lisp")
(load-theme 'tramp t nil) ; Load an available theme

1. Put a copy of "dired.el.gz" in ~/.emacs.d/lisp

2. emacs &

3. M-x describe-variable RET after-init-hook


        The variable `after-init-hook' then appears to be corrupted:

after-init-hook is a variable defined in ‘startup.el’.
Its value is (#[0 "\305\211\b\235\203\306\b\"\301\307!\210\210	\205(\n\205 \v\205 \310 ?\311 \210\312\211)\207"
     [command-line-args desktop-save-mode desktop-restore-frames initial-window-system inhibit-startup-screen "--no-desktop" delete 0 daemonp desktop-read t]
     4]
 x-wm-set-size-hint)


        Thanks.

Re: Local elisp library files and variable corruption

[Eli Zaretskii]

> From: Live System User <nyc4bos@aol.com>
> Date: Fri, 24 Jun 2016 14:59:05 -0400
> 
> 3. M-x describe-variable RET after-init-hook
> 
> 
>         The variable `after-init-hook' then appears to be corrupted:
> 
> after-init-hook is a variable defined in ‘startup.el’.
> Its value is (#[0 "\305\211\b\235\203\306\b\"\301\307!\210\210	\205(\n\205 \v\205 \310 ?\311 \210\312\211)\207"
>      [command-line-args desktop-save-mode desktop-restore-frames initial-window-system inhibit-startup-screen "--no-desktop" delete 0 daemonp desktop-read t]
>      4]
>  x-wm-set-size-hint)

Why do you say this is corrupted?  It looks like bytecode to me.

Re: Local elisp library files and variable corruption

[Noam Postavsky]

On Fri, Jun 24, 2016 at 3:16 PM, Eli Zaretskii <eliz@gnu.org> wrote:
>> From: Live System User <nyc4bos@aol.com>
>> Date: Fri, 24 Jun 2016 14:59:05 -0400
>>
>> 3. M-x describe-variable RET after-init-hook
>>
>>
>>         The variable `after-init-hook' then appears to be corrupted:
>>
>> after-init-hook is a variable defined in ‘startup.el’.
>> Its value is (#[0 "\305\211 \235\203\306 \"\301\307!\210\210  \205(\n\205  \205 \310 ?\311 \210\312\211)\207"
>>      [command-line-args desktop-save-mode desktop-restore-frames initial-window-system inhibit-startup-screen "--no-desktop" delete 0 daemonp desktop-read t]
>>      4]
>>  x-wm-set-size-hint)
>
> Why do you say this is corrupted?  It looks like bytecode to me.
>

Specifically the compiled form of the anonymous function added by
desktop.el (look near the end):

(add-hook
  'after-init-hook
  (lambda ()
    (let ((key "--no-desktop"))
      (when (member key command-line-args)
...

Re: Local elisp library files and variable corruption

[Live System User]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Live System User <nyc4bos@aol.com>
>> Date: Fri, 24 Jun 2016 14:59:05 -0400
>> 
>> 3. M-x describe-variable RET after-init-hook
>> 
>> 
>>         The variable `after-init-hook' then appears to be corrupted:
>> 
>> after-init-hook is a variable defined in ‘startup.el’.
>> Its value is (#[0 "\305\211\b\235\203\306\b\"\301\307!\210\210	\205(\n\205 \v\205 \310 ?\311 \210\312\211)\207"
>>      [command-line-args desktop-save-mode desktop-restore-frames initial-window-system inhibit-startup-screen "--no-desktop" delete 0 daemonp desktop-read t]
>>      4]
>>  x-wm-set-size-hint)
>
> Why do you say this is corrupted?  It looks like bytecode to me.

Aha!

Another poster, Noam, pointed out that this is from the compiled
form of the anonymous function added by desktop.el.gz.

How does one go about getting `describe-variable' to return the
non-bytecode version of a variable, including, in this case, the
add-hook `after-init-hook' value from desktop.el.gz?

Thanks.

Re: Local elisp library files and variable corruption

[Noam Postavsky]

On Sat, Jun 25, 2016 at 4:37 PM, Live System User <nyc4bos@aol.com> wrote:
> How does one go about getting `describe-variable' to return the
> non-bytecode version of a variable, including, in this case, the
> add-hook `after-init-hook' value from desktop.el.gz?

You can't, the information is not recorded anywhere. I think the best
solution is to give a name to that function in desktop.el. Then you
would see something like

    Its value is (desktop-maybe-restore x-wm-set-size-hint)

Re: Local elisp library files and variable corruption

[Tom]

Eli Zaretskii <eliz <at> gnu.org> writes:
> > 
> >         The variable `after-init-hook' then appears to be corrupted:
> > 
> > after-init-hook is a variable defined in ‘startup.el’.
> > Its value is (#[0 "\305\211\b\235\203\306\b\"\301\307!\210\210
\205(\n\205 \v\205 \310 ?\311 \210\312\211)\207"
> >      [command-line-args desktop-save-mode desktop-restore-frames
initial-window-system
> inhibit-startup-screen "--no-desktop" delete 0 daemonp desktop-read t]
> >      4]
> >  x-wm-set-size-hint)
> 
> Why do you say this is corrupted?  It looks like bytecode to me.
> 

Wouldn't it be better if describe-variable didn't just dump the bytecode
there with octal sequences and stuff, confusing users who don't know
what that is? 

If it can detect a bytecoded value then it could say the value is
bytecoded and there could be a button or something to show the actual
bytecode if somebody wants to see it.