The boolean variable
truncate-lines controls whether continuation lines are displayed or not. I use this when I am checking some log file where the very long lines are truncated thanks to a previous
(setq truncate-lines t). This is convenient since the relevant contents is usually at the beginning of the lines. However I sometimes need to see the end of the inspected lines and I'll occasionally toggle
truncate-lines on and off (this is done in code temporarily bound to a function key).
The problem is that toggling
truncate-lines on and off does not update the display unless I do some editing, or move the cursor far enough, or .. I don't know what. I tried to insert a
(redisplay t) in my toggling code but this is not enough.
What bit of elisp magic will cause the display to be updated according to the new value of
truncate-lines once it is changed? And, by the way, is the lack of immediate update a bona fide bug?
How to reproduce the problem: After some investigation, it seems that the problem appears because I invoke the toggle via some key binding and not by
M-x. Here is a test file for you to download. Start with
emacs -Q test_file, then
eval-defun the first expression. Now
M-x ttl does the toggle ok but on my machine hitting
CTRL l (now bound to
ttl) does the toggle without redisplay. If I move to end of buffer, the redisplay is activated.
FWIW I use emacs 24.5.1
Added Jan. 5th: it turns out that the behaviour described above is due to a minor bug that will be fixed in Emacs 25, see here. In principle there is nothing wrong with changing
truncate-lines directly without going through