Merge pull request #33 from knu/pr-coffee-compiled-file-name

Add a function coffee-compiled-file-name for ease of scripting.

README.md

@@ -190,6 +190,13 @@ compile-on-save minor mode in `coffee-mode`.  To enable it by default:
 
     (add-hook 'coffee-mode-hook '(lambda () (coffee-cos-mode t)))
 
+To enable it only if it looks like you may want to:
+
+    (add-hook 'coffee-mode-hook '(lambda ()
+                                   (and (file-exists-p (buffer-file-name))
+                                        (file-exists-p (coffee-compiled-file-name))
+                                        (coffee-cos-mode t))))
+
 ### coffee-repl
 
 Starts a repl in a new buffer using `coffee-command`.
@@ -222,12 +229,11 @@ Naturally. Example:
       (setq coffee-command "~/dev/coffee"))
 
       ;; Compile '.coffee' files on every save
-      (add-hook 'after-save-hook
-          '(lambda ()
-             (when (string-match "\.coffee$" (buffer-name))
-              (coffee-compile-file))))
+      (and (file-exists-p (buffer-file-name))
+           (file-exists-p (coffee-compiled-file-name))
+           (coffee-cos-mode t))))
 
-    (add-hook 'coffee-mode-hook '(lambda () (coffee-custom)))
+    (add-hook 'coffee-mode-hook 'coffee-custom))
 
 ## Configuration
 

coffee-mode.el

@@ -156,12 +156,17 @@ path."
 
   (pop-to-buffer "*CoffeeREPL*"))
 
+(defun coffee-compiled-file-name (&optional filename)
+  "Returns the name of the JavaScript file compiled from a CoffeeScript file.
+If FILENAME is omitted, the current buffer's file name is used."
+  (concat (file-name-sans-extension (or filename (buffer-file-name))) ".js"))
+
 (defun coffee-compile-file ()
   "Compiles and saves the current file to disk. Doesn't open in a buffer.."
   (interactive)
   (let ((compiler-output (shell-command-to-string (coffee-command-compile (buffer-file-name)))))
     (if (string= compiler-output "")
-        (message "Compiled and saved %s" (concat (substring (buffer-file-name) 0 -6) "js"))
+        (message "Compiled and saved %s" (coffee-compiled-file-name))
       (message (car (split-string compiler-output "[\n\r]+"))))))
 
 (defun coffee-compile-buffer ()