Beef up program-running helpers

* .emacs (my/run-strip-newline): New escape hatch, to let my/run DTRT
most of the time and spare most callers the cognitive load.
(my/run): Heed it.  Document.
(my/kill-command): New helper; meant for programmatic use where
arglists are manipulated as lists, and and no shell escaping is
required.
(my/kill-date, my/describe-revision): Use it.
(my/kill-shell): Document, to disambiguate with my/kill-command.

1 files changed, 26 insertions, 15 deletions

diff --git a/.emacs b/.emacs
index b3866da..ff0dce1 100644
--- a/.emacs
+++ b/.emacs
@@ -189,13 +189,25 @@
 (defun my/read (prompt default)
   (read-string (format-prompt prompt default) nil nil default))
 
+(defvar my/run-strip-newline t
+  "Whether `my/run' will remove a trailing newline from a command's output.")
+
 (defun my/run (program &rest args)
-  (let ((handler (lambda (status)
-                   (unless (eq status 0)
-                     (user-error
-                      "%s returned %d:\n%s"
-                      program status (buffer-string))))))
-    (apply 'process-lines-handling-status program handler args)))
+  "Return output from 'PROGRAM [ARGS…]'.
+Raise a user error if the command fails.  Heed `my/run-strip-newline'."
+  (with-temp-buffer
+    (let* ((status (apply 'call-process program nil t nil args))
+           (output (buffer-string)))
+      (if (eq status 0)
+          (if my/run-strip-newline
+              (string-remove-suffix "\n" output)
+            output)
+        (user-error "%s returned %d:\n%s" program status output)))))
+
+(defun my/kill-command (program &rest args)
+  "Send output from PROGRAM to kill-ring.
+See `my/run' for details, e.g. status handling and output massaging."
+  (my/kill (apply 'my/run program args)))
 
 (defun my/kill-date (date format)
   (interactive
@@ -203,8 +215,7 @@
        (list (my/read "Date spec?" "today")
              (my/read "Format?" "%F"))
      (list "today" "%F")))
-  (my/kill
-   (car (my/run "date" (concat "-d" date) (concat "+" format)))))
+  (my/kill-command "date" (concat "-d" date) (concat "+" format)))
 
 (defun my/kill-filename ()
   (interactive)
@@ -220,6 +231,10 @@
       (my/kill (buffer-string)))))
 
 (defun my/kill-shell (command)
+  "Send output from COMMAND to kill-ring.
+Meant for interactive prompting for full commands passed to a shell.
+For Lisp use, prefer `my/kill-command', where arguments are passed via a
+list and require no escaping."
   (interactive (list (read-shell-command "Shell command: ")))
   (with-temp-buffer
     (call-process-shell-command command nil t)
@@ -436,13 +451,9 @@
 (defun my/describe-revision (rev)
   "Format a Git revision in a format suitable for changelogs."
   (interactive
-   (list (let ((rev (my/revision-at-point)))
-           (read-string (format-prompt "Revision" rev)
-                        nil nil rev))))
-  (my/kill (string-trim
-            (shell-command-to-string
-             (format "git show --no-patch --date=short --format='%s' %s"
-                     "%cd \"%s\" (%h)" rev)))))
+   (list (my/read "Revision" (my/revision-at-point))))
+  (my/kill-command
+   "git" "show" "--no-patch" "--date=short" "--format=%cd \"%s\" (%h)" rev))
 
 ;;; Major modes configuration.