Re: invisible

[martin rudalics <rudalics@gmx.at>]

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 >>>(put-text-property 6 7 `invisible t)
 >>>(put-text-property 12 13 `invisible t)
 >>>(put-text-property 18 19 `invisible t)
 >>>(put-text-property 24 25 `invisible t)
 >>>(put-text-property 30 31 `invisible t)

These will cause problems with `forward-line'.

I'd propose to use

(add-text-properties 6 7 '(invisible t rear-nonsticky t))
(add-text-properties 12 13 '(invisible t rear-nonsticky t))
(add-text-properties 18 19 '(invisible t rear-nonsticky t))
(add-text-properties 24 25 '(invisible t rear-nonsticky t))
(add-text-properties 30 31 '(invisible t rear-nonsticky t))

instead.

 >>>C-p beginning of line4.  Why did we skip line5?
 >>>C-p beginning of line2.  Skipped line3.

See above.  Verify by running (forward-line -1) on these.  Your results
may differ according to the value of `track-eol'.

 >>This behavior still exists in GNU Emacs 23.0.50.4 (i686-pc-linux-gnu,
 >>GTK+ Version 2.12.0) of 2007-11-09 on escher.[1]  In addition, starting
 >>with the cursor at (point-min), the line number indicator in the mode
 >>line displays L1, and it continues to display L1 as you advance either
 >>by C-n or by C-f until it reaches the `l' of `line7', then it changes to
 >>L7.  From there if you type C-b moving point to just after `6', the mode
 >>line displays L6.  Now continuing backwards either by C-p or C-b the
 >>mode line usually continues to display L6, even at (point-min).  Typing
 >>C-b again here then changes the display to L1.

We have been discussing this at the beginning of this year but I don't
recall the thread.  I seem to recall that Emacs tries to optimize line
number calculations as long as the buffer is not modified.

 > In current development Emacs, the cursor stays put, i.e., C-p is a no-op
 > here; the same goes for every position in line 3, except the beginning
 > of the line: here C-p goes to the beginning of line 1 (the parenthetical
 > comment doesn't make sense, unless it is a typo for line 1, or maybe he
 > means the mode line should display L2 instead of L3, even though the
 > cursor stays put).

This seems like a bug in `line-move-finish', please try the attached
patch (untested).

 >>At the beginning of line 3, C-e goes to "i" in line 3.
 >>	(should go to the end of line 3)
 >
 >
 > In current development Emacs, the cursor goes to the end of line 1
 > (anywhere else on line 3, C-e goes to the end of line 3).  On the other
 > hand, C-a at the beginning of line 3 goes to "i" in line 3 (elsewhere it
 > goes to the beginning of the line, so that repeatedly typing C-a
 > starting from the beginning of line 3 makes the cursor oscillate between
 > the first and second columns of the line).
 >
 >
 >>(2) If line-move-ignore-invisible is t:
 >>
 >>At the end of line 1, C-n goes to the beginning of line 3.
 >>	(should go to the end of line 3)
 >>At the end of line 4, C-p goes to the beginning of line 3.
 >>	(should go to the end of line 3)
 >>At the beginning of the line 3, C-e goes to "i" in line 3.
 >>	(should go to the end of line 3)

There's likely also a bug in `line-move-to-column': `move-to-column'
apparently skips invisible text (I didn't find any documentation for
that).  I tried to fix it in a really awkward way in the same patch.

[-- Attachment #2: simple.patch --]
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*** simple.el.~1.888.~	Sat Nov 10 09:23:20 2007
--- simple.el	Sun Nov 18 16:02:42 2007
***************
*** 3862,3868 ****
  	     (save-excursion
  	       ;; Like end-of-line but ignores fields.
  	       (skip-chars-forward "^\n")
! 	       (while (and (not (eobp)) (invisible-p (point)))
  		 (goto-char (next-char-property-change (point)))
  		 (skip-chars-forward "^\n"))
  	       (point))))
--- 3862,3869 ----
  	     (save-excursion
  	       ;; Like end-of-line but ignores fields.
  	       (skip-chars-forward "^\n")
! 	       (while (and line-move-ignore-invisible
! 			   (not (eobp)) (invisible-p (point)))
  		 (goto-char (next-char-property-change (point)))
  		 (skip-chars-forward "^\n"))
  	       (point))))
***************
*** 3940,3948 ****
  This function works only in certain cases,
  because what we really need is for `move-to-column'
  and `current-column' to be able to ignore invisible text."
!   (if (zerop col)
!       (beginning-of-line)
      (move-to-column col))

    (when (and line-move-ignore-invisible
  	     (not (bolp)) (invisible-p (1- (point))))
--- 3941,3956 ----
  This function works only in certain cases,
  because what we really need is for `move-to-column'
  and `current-column' to be able to ignore invisible text."
!   (cond
!    ((zerop col)
!     (beginning-of-line))
!    (line-move-ignore-invisible
      (move-to-column col))
+    (t
+     ;; Tedious.
+     (save-restriction
+       (narrow-to-region (line-beginning-position) (line-end-position))
+       (move-to-column col))))

    (when (and line-move-ignore-invisible
  	     (not (bolp)) (invisible-p (1- (point))))

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