* match.c (h_fun, v_fun): Bugfix! copy_list should be used for copying

the bindings, not copy_alist. Otherwise functions cannot destructively
update a binding, which is useless. We want a function not to
manipulate the binding list, but to be able to manipulate the
contents of bindings.
(match_files_ctx): Declaration moved ahead of match_line.
(v_fun): Forward declaration added.
(match_line): Allow vertical functions to be called from
a horizontal context, in a limited way.

* txr.1: Mention the possibility of a call from a horizontal
context falling back on a vertical function.

1 files changed, 7 insertions, 2 deletions

diff --git a/txr.1 b/txr.1
index ed5832c5..f8197650 100644
--- a/txr.1
+++ b/txr.1
@@ -3021,8 +3021,13 @@ Example:
 
   Output:         fun="horizontal"
 
-A call made in a clearly horizontal context will ignore
-the vertical definition, if any, and require the horizontal function.
+A call made in a clearly horizontal context will prefer the
+horizontal function, and only fall back on the vertical one
+if the horizontal one doesn't exist. (In this fall-back case,
+the vertical function is called with empty data; it is useful
+for calling vertical functions which process arguments and
+produce values.)
+
 In the next example, the call is followed by trailing material,
 placing it in a horizontal context. Leading material will
 do the same thing: