Re: [Jed-users-l] editing symbolic links

["John E. Davis" <davis@xxxxxxxxxxxxx>]

Ulli Horlacher <framstag@xxxxxxxxxxxxxxxxxxxx> wrote:
> You mean, there are 3 files?
>
> foo -> /tmp/bar
> bar
> /tmp/bar
>
> I see here no problem at all?
> Editing foo leads to:
>
> foo -> /tmp/bar
> /tmp/bar~

Suppose that there are 3 files in /tmp,

   /tmp/foo --> /some/other/dir/bar
   /tmp/zzz
   /tmp/bar

and two others in /some/other/dir:

   /some/other/dir/bar
   /some/other/dir/zzz

Note that /tmp/foo is a symlink.

Now suppose the current directory is /home/ulli/ and from there you
edit /tmp/foo:

   %unix> pwd
   /home/ulli
   %unix> jed /tmp/foo

In the current scheme, the list_buffers will show:

    Flags     umask   Buffer Name             Dir/File
    ----------- 0000    "*scratch*"         /home/ulli/
    -----U---AM 0000    "foo"               /tmp/foo

Now, suppose you use the find_file function to edit another file.  You
will see the prompt:

    Find file: /tmp/

Now type zzz and press enter.  The list_buffers function will show:

    Flags     umask   Buffer Name             Dir/File
    ----------- 0000    "*scratch*"         /home/ulli/
    -----U---AM 0000    "foo"               /tmp/foo
    -----U---AM 0000    "zzz"               /tmp/zzz

So you make some changes to foo and zzz and save the results.  This
will lead to the following files:

   /tmp/foo --> /some/other/dir/bar  (foo still has the same link name)
   /tmp/bar                          (unchanged, since it was not edited)
   /tmp/zzz                          (changed)
   /tmp/zzz~                         (previous version)
   /some/other/dir/bar               (modified, via foo)
   /some/other/dir/bar~              (the backup file)
   /some/other/dir/zzz               (unchanged)


Now consider what would happen in your scheme which uses not the link
foo, but the target of the link as the basis for buffer names and
directories:

   %unix> pwd
   /home/ulli
   %unix> jed /tmp/foo

The list_buffers command would show:

    Flags     umask   Buffer Name             Dir/File
    ----------- 0000    "*scratch*"         /home/ulli/
    -----U---AM 0000    "bar"               /some/other/dir/bar

Any reference to /tmp has been lost.  Use find_file to load zzz:

    -----U---AM 0000    "zzz"               /tmp/zzz

The prompt will read:

    Find file: /some/other/dir/

If your intent is to edit /tmp/zzz, you will have to change
/some/other/dir/ to /tmp/.  On the other hand, if you blindly assume
that since you originally loaded a file from /tmp, and you are now
loading another file from that buffer, then you might enter zzz at the
prompt without realizing that the prompt is different.  As a result,
you will be editing the wrong file.

For these reasons, I think that using the target of a symlink as the
filename is conceptually more confusing.  On the other hand, if your
intent is to edit /some/other/dir/bar, why not edit it directly?

I hope I have explained the rationale for the current behavior.

Thanks,
--John
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