(with-temp-file): New macro.

1 files changed, 48 insertions, 2 deletions

diff --git a/lisp/subr.el b/lisp/subr.el
index a3357c71863..7a5c9c69a6e 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -732,7 +732,7 @@ Wildcards and redirection are handled as usual in the shell."
    (t
     (start-process name buffer shell-file-name shell-command-switch
                    (mapconcat 'identity args " ")))))
-
+
 (defmacro with-current-buffer (buffer &rest body)
   "Execute the forms in BODY with BUFFER as the current buffer.
 The value returned is the value of the last form in BODY."
@@ -740,6 +740,52 @@ The value returned is the value of the last form in BODY."
     (set-buffer ,buffer)
     . ,body))
 
+(defmacro with-temp-file (file &rest forms)
+  "Create a new buffer, evaluate FORMS there, and write the buffer to FILE.
+Return the value of FORMS.
+If FILE is nil, just evaluate FORMS and don't save anything.
+If FILE is t, return the buffer contents as a string."
+  (let ((temp-file (make-symbol "temp-file"))
+        (temp-buffer (make-symbol "temp-buffer"))
+        (temp-results (make-symbol "temp-results")))
+    `(save-excursion
+       (let* ((,temp-file ,file)
+              (default-major-mode 'fundamental-mode)
+              (,temp-buffer
+               (progn
+                 (set-buffer
+                  (get-buffer-create
+                   (generate-new-buffer-name " *temp file*")))
+                 (buffer-disable-undo (current-buffer))
+                 (current-buffer)))
+              ,temp-results)
+         (unwind-protect
+             (progn
+               (setq ,temp-results (progn ,@forms))
+               (cond
+                ;; Don't save anything.
+                ((null ,temp-file)
+                 ,temp-results)
+                ;; Return the buffer contents.
+                ((eq ,temp-file t)
+                 (set-buffer ,temp-buffer)
+                 (buffer-string))
+                ;; Save a file.
+                (t
+                 (set-buffer ,temp-buffer)
+                 ;; Make sure the directory where this file is
+                 ;; to be saved exists.
+                 (when (not (file-directory-p
+                             (file-name-directory ,temp-file)))
+                   (make-directory (file-name-directory ,temp-file) t))
+                 ;; Save the file.
+                 (write-region (point-min) (point-max)
+                               ,temp-file nil 'nomesg)
+                 ,temp-results)))
+           ;; Kill the buffer.
+           (when (buffer-name ,temp-buffer)
+             (kill-buffer ,temp-buffer)))))))
+
 (defmacro with-output-to-string (&rest body)
   "Execute BODY, return the text it sent to `standard-output', as a string."
   `(let ((standard-output (get-buffer-create " *string-output*")))
@@ -799,7 +845,7 @@ If SEPARATORS is absent, it defaults to \"[ \\f\\t\\n\\r\\v]+\"."
               (cons (substring string start)
                     list)))
     (nreverse list)))
-
+
 (defun shell-quote-argument (argument)
   "Quote an argument for passing as argument to an inferior shell."
   (if (eq system-type 'ms-dos)