comint-insert-previous-argument counts args from start or from end

This function is invoked in shell-mode by the user, and is meant to
emulate what M-. does in zsh and bash: it inserts an argument from a
previous command.  Without a prefix argument, it inserts the last arg
from the previous command; with an argument INDEX, it inserts the
INDEX-th argument.  bash counts from the start, while zsh counts from
the end.  This patch adds a variable
`comint-insert-previous-argument-from-end' that emulates the zsh
behavior if non-nil.

* lisp/comint.el (comint-arguments): can take in negative arguments to count
  from the end, same as indexing in python.
  (comint-insert-previous-argument): if
  comint-insert-previous-argument-from-end is non-nil, INDEX counts
  arguments from the end; if nil, from the beginning
  (Bug#25271)
* etc/NEWS: Document this.

1 files changed, 10 insertions, 0 deletions

diff --git a/etc/NEWS b/etc/NEWS
index 5a3a27ee4af..8bf1da470fc 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -190,6 +190,16 @@ navigation and editing of large files.
 It now treats the optional 2nd argument to mean that the URL should be
 shown in the currently selected window.
 
+** Comint
+*** 'comint-insert-previous-argument' knows how to count args
+from the beginning or from the end.  This is useful because
+'comint-insert-previous-argument' exists to emulate M-. in bash and zsh; and
+bash counts from the start while zsh counts from the end.
+
+*** New variable 'comint-insert-previous-argument-from-end' controls whether
+args passed to 'comint-insert-previous-argument' count from the beginning or
+from the end
+
 ** Flymake
 
 +++