Re: Mode to display information in the topmost line of a window

[Lennart Borgman <lennart.borgman@gmail.com>]

On Thu, Jul 30, 2009 at 5:47 PM, Geralt<usr.gentoo@googlemail.com> wrote:
> On Thu, Jul 30, 2009 at 5:19 PM, Tassilo Horn<tassilo@member.fsf.org> wrote:
>> Geralt <usr.gentoo@googlemail.com> writes:
>>
>> Hi Geralt,
>>
>>> iirc there's a mode in Emacs to display some information in the
>>> topmost line of a window, but I don't recall its name anymore.  Do you
>>> know what I'm talking about?
>>
>> Yes, but it's no mode, it's a simple variable you can set.
>>
>> ,----[ C-h v header-line-format RET ]
>> | header-line-format is a variable defined in `C source code'.
>> | Its value is nil
>> |
>> |   Automatically becomes buffer-local when set in any fashion.
>> |   This variable is potentially risky when used as a file local variable.
>> |
>> | Documentation:
>> | Analogous to `mode-line-format', but controls the header line.
>> | The header line appears, optionally, at the top of a window;
>> | the mode line appears at the bottom.
>> `----
>>
>>> And if yes do you know if it's possible to display ElDoc's output in
>>> this line instead of the echo area?
>>
>> I guess you could redefine the function `eldoc-message' and set
>> `header-line-format' there.
>>
>> Bye,
>> Tassilo
>>
>>
>>
>>
> Hi Tassilo,
>
> thanks, that helped me a lot! From what I've found it's as simple as
> changing eldoc-message to:
>
> (defun eldoc-message (&rest args)
>  (let ((omessage eldoc-last-message))
>    (setq eldoc-last-message
>          (cond ((eq (car args) eldoc-last-message) eldoc-last-message)
>                ((null (car args)) nil)
>                ;; If only one arg, no formatting to do, so put it in
>                ;; eldoc-last-message so eq test above might succeed on
>                ;; subsequent calls.
>                ((null (cdr args)) (car args))
>                (t (apply 'format args))))
>    ;; In emacs 19.29 and later, and XEmacs 19.13 and later, all messages
>    ;; are recorded in a log.  Do not put eldoc messages in that log since
>    ;; they are Legion.
>    ;; Emacs way of preventing log messages.
>    (let ((message-log-max nil))
>      (cond (eldoc-last-message (setq header-line-format eldoc-last-message))
>            (omessage (message nil)))))
>  eldoc-last-message)
>
>
>
> What's the prefered way to overwrite a function? Just putting this one
> into .emacs?


Looking through it more carefully and submitting a patch to Emacs.