How to know the value of a non interactive function?

How to know the value of a non interactive function?

[Rodolfo Medina]

Pardon the basicness of my question: I wish to know what value is returned by
the `window-height' function in my buffer: how can I achieve that?

Thanks for any help
Rodolfo

Re: How to know the value of a non interactive function?

[Anders Wirzenius]

Rodolfo Medina <rodolfo.medina@gmail.com> writes:

> Pardon the basicness of my question: I wish to know what value is returned by
> the `window-height' function in my buffer: how can I achieve that?
> 
> Thanks for any help
> Rodolfo

type
(window-height)
in the buffer and press C-xC-e

-- 
Anders

Re: How to know the value of a non interactive function?

[Tassilo Horn]

Rodolfo Medina <rodolfo.medina@gmail.com> writes:

Hi Rodolfo,

> Pardon the basicness of my question: I wish to know what value is
> returned by the `window-height' function in my buffer: how can I
> achieve that?

With `M-:' you can evaluate arbitrary lisp code which has access to the
current environment (buffer with point and mark, window, etc.) where you
hit `M-:'.  So in your case

  M-: (window-height)

should do the trick.  (BTW: With M-TAB you have autocompletion for any
known lisp symbol there.)

Bye,
Tassilo
-- 
Richard Stallman gets 9 bits to the byte.

window-height function lies! (was: How to know the value of a non interactive function?)

[Rodolfo Medina]

Rodolfo Medina <rodolfo.medina@gmail.com> writes:

>> Pardon the basicness of my question: I wish to know what value is
>> returned by the `window-height' function in my buffer: how can I
>> achieve that?



Anders Wirzenius <anders@no.email.thanks.invalid> writes:

> type
> (window-height)
> in the buffer and press C-xC-e


Peter Dyballa <Peter_Dyballa@Web.DE> writes:

> Or in the *scratch* buffer, and only there, C-j.


Tassilo Horn <tassilo@member.fsf.org> writes:

> With `M-:' you can evaluate arbitrary lisp code which has access to the
> current environment (buffer with point and mark, window, etc.) where you
> hit `M-:'.  So in your case
>
>   M-: (window-height)
>
> should do the trick.



Thanks to Anders, Peter and Tassilo for their help.

But, the remarkable result is that, the value returned by window-height turns
to be *false* when the buffer contains a line longer that the screen width (a
line that continues on the following line).  Besides, window-height fails in
info buffers and TeX mode buffers, that contain chapter and node titles with
bigger characters.

This is probably related to the malfunction of the
`scroll-preserve-screen-position' variable and of all lisp codes (pager.el,
scroll-in-place.el, etc.) that want to keep point `in place' when scrolling
(see my thread on the matter).

The problem seems to me to be quite a serious one.  Comments (and possible
solutions) welcome upon this matter.

Thanks
Rodolfo

Re: window-height function lies!

[Nikolaj Schumacher]

Rodolfo Medina <rodolfo.medina@gmail.com> wrote:

> But, the remarkable result is that, the value returned by
> window-height turns to be *false* when the buffer contains a line
> longer that the screen width (a line that continues on the following
> line).

I was a little confused by this sentence at first.  Because no matter
how long I made the lines, `window-height' remained the same.  But then
I understood, you think it should get smaller, because fewer lines are
displayed, right?  However `window-height' is related to the window and
independent of the buffer.  It relates to `move-to-window-line', not
`goto-line'.

You might want to use:

(1+ (count-lines (window-start) (window-end)))


regards,
Nikolaj Schumacher

Re: window-height function lies!

[Rodolfo Medina]

Rodolfo Medina <rodolfo.medina@gmail.com> wrote:

>> But, the remarkable result is that, the value returned by
>> window-height turns to be *false* when the buffer contains a line
>> longer that the screen width (a line that continues on the following
>> line).



Nikolaj Schumacher <me@nschum.de> writes:

> I was a little confused by this sentence at first.  Because no matter
> how long I made the lines, `window-height' remained the same.  But then
> I understood, you think it should get smaller, because fewer lines are
> displayed, right?


Yes, that's right.


> However `window-height' is related to the window and
> independent of the buffer.  It relates to `move-to-window-line', not
> `goto-line'.
>
> You might want to use:
>
> (1+ (count-lines (window-start) (window-end)))


All right that works for `too long' lines.  But still window-height fails in
info buffers and TeX mode buffers, that contain chapter and node titles with
bigger characters.  Any way to solve that?

Thanks
Rodolfo

Re: window-height function lies!

[Nikolaj Schumacher]

Rodolfo Medina <rodolfo.medina@gmail.com> wrote:

> All right that works for `too long' lines.  But still window-height fails in
> info buffers and TeX mode buffers, that contain chapter and node titles with
> bigger characters.  Any way to solve that?

I don't have much experience with differently sized characters, but it
should still work.  `count-lines' will measure actual lines, and
`window-height' will measure the window height in "regular" lines.


regards,
Nikolaj Schumacher

Bind the value of a function to a variable (was: window-height function lies!)

[Rodolfo Medina]

Nikolaj Schumacher <me@nschum.de> writes:

> You might want to use:
>
> (1+ (count-lines (window-start) (window-end)))



Thanks.
I want to try to bind this to a variable, but don't know the right syntax.  I
want to do something like:

(setq scroll-default-lines (1+ (count-lines (window-start) (window-end))))

, but get error.  How can I do that the right way?

Thanks
Rodolfo

Re: Bind the value of a function to a variable

[Nikolaj Schumacher]

Rodolfo Medina <rodolfo.medina@gmail.com> wrote:

> Thanks.
> I want to try to bind this to a variable, but don't know the right syntax.  I
> want to do something like:
>
> (setq scroll-default-lines (1+ (count-lines (window-start) (window-end))))
>
> , but get error.  How can I do that the right way?

What error do you get?
You are correctly /assigning/ the value to a variable.  To /bind/ a
variable, you'll need to use `let'.

(let ((scroll-default-lines
           (1+ (count-lines (window-start) (window-end)))))
  ;; use scroll-default-lines here
  (setq scroll-default-lines 'something-else))

regards,
Nikolaj Schumacher