Re: something like linum.el ought to be added

[Markus Triska <markus.triska@gmx.at>]

Richard Stallman <rms@gnu.org> writes:

> Would someone like to try implementing this?

A first try follows. In addition, here is a version of linum.el that
depends on the patch and seems to work as intended:

   http://stud4.tuwien.ac.at/~e0225855/linum/linum-cvs.el

Other versions are of course still available from the project page.

2007-09-16  Markus Triska  <markus.triska@gmx.at>

	* xdisp.c (redisplay_window): Invoke new hook,
	window-bottom-change-functions, when visibility changes may have
	altered the position of the bottom of the window.
	(syms_of_xdisp): add window-bottom-change-functions

diff --git a/src/xdisp.c b/src/xdisp.c
index 618a538..80b973c 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -232,6 +232,7 @@ extern Lisp_Object Qhelp_echo;
 
 Lisp_Object Qoverriding_local_map, Qoverriding_terminal_local_map;
 Lisp_Object Qwindow_scroll_functions, Vwindow_scroll_functions;
+Lisp_Object Qwindow_bottom_change_functions, Vwindow_bottom_change_functions;
 Lisp_Object Qredisplay_end_trigger_functions, Vredisplay_end_trigger_functions;
 Lisp_Object Qinhibit_point_motion_hooks;
 Lisp_Object QCeval, QCfile, QCdata, QCpropertize;
@@ -12880,6 +12881,10 @@ redisplay_window (window, just_this_one_p)
        && XFASTINT (w->last_modified) >= MODIFF
        && XFASTINT (w->last_overlay_modified) >= OVERLAY_MODIFF);
 
+  if (!current_matrix_up_to_date_p
+      && !NILP(Vwindow_bottom_change_functions))
+      safe_run_hooks (Qwindow_bottom_change_functions);
+
   buffer_unchanged_p
     = (!NILP (w->window_end_valid)
        && !current_buffer->clip_changed
@@ -23866,6 +23871,9 @@ syms_of_xdisp ()
   staticpro (&Qwindow_scroll_functions);
   Qwindow_scroll_functions = intern ("window-scroll-functions");
 
+  staticpro (&Qwindow_bottom_change_functions);
+  Qwindow_bottom_change_functions = intern ("window-bottom-change-functions");
+
   staticpro (&Qredisplay_end_trigger_functions);
   Qredisplay_end_trigger_functions = intern ("redisplay-end-trigger-functions");
 
@@ -24173,6 +24181,11 @@ and its new display-start position.  Note that the value of `window-end'
 is not valid when these functions are called.  */);
   Vwindow_scroll_functions = Qnil;
 
+  DEFVAR_LISP ("window-bottom-change-functions", &Vwindow_bottom_change_functions,
+    doc: /* List of functions to call when visibility changes may have altered
+the position of the bottom of the window. */);
+  Vwindow_bottom_change_functions = Qnil;
+
   DEFVAR_LISP ("redisplay-end-trigger-functions", &Vredisplay_end_trigger_functions,
     doc: /* Functions called when redisplay of a window reaches the end trigger.
 Each function is called with two arguments, the window and the end trigger value.