I'm writing something to try and help us cut down on the system resources used by emacsen, calling it 'load-manager-unload-feature', intending to eventually make a nice gui for it (but, for now, it's basically just a different interactive interface on `unload-feature') It would make it a heck of a lot easier to do this, if we added something like this to loadhist.el, where `unload-feature' is defined: (define-error 'cannot-unload-feature "error to signal when a feature cannot be unloaded") .. and modify `unload-feature', to make it signal that error, when a feature cannot be unloaded because some loaded libraries are depending on it. but i didn't think that was the best name for the error. any suggestions? -- sean champ here's a snapshot of the load-manager code so far: ;; load-manager.el (defvar load-manager-feature-history nil "history used by `load-manager-unload-feature") ;; haven't integrated this error type yet, but here it is: (define-error 'cannot-unload-feature "error to signal when a feature cannot be unloaded") (defun load-manager-unload-feature (feature) "attempt to unload FEATURE If the feature is required by any other loaded code, a warning will be signaled [was implemented, but presently isn't]. also see: `unload-feature' " (interactive (list (intern-soft (completing-read "unload feature: " obarray #'(lambda (obj) (and (featurep obj) (feature-file obj))) t nil 'load-manager-feature-history)))) ;; i need to use a `condition-case' here, instead, ;; but this hopefully makes the point of what i'm trying to do: ;; i'm trying to change what happens when a feature cannot be unloaded. (catch 'unable-to-unload (if (feature-file feature) (condition-case err (unload-feature feature) ;; the error-handler makes up the most of this (error (let ((errmsg (car (cdr err)))) ; DEBUG: (print errmsg (current-buffer)) ;; check to make sure it's the error that we're looking for ... (if (and errmsg (string-match (format "^Loaded libraries (\\(.*\\)) depend on %s" feature) errmsg)) (let ((dependents (split-string ;; we get "\"foo"\" for each thing that we want from ;; the the string-match. this isn't the best way to ;; get rid of those quotes, but it works. (replace-in-string (match-string 1 errmsg) "\"" "") " ")) dependv) ;; hope that the library name of the dependent library is the same as ;; that of a feature provided it; if it is, ask user if that ;; dependent feature should be unloaded. ; DEBUG: (print dependents (current-buffer)) (while (progn (setq dependv (intern-soft (car dependents)) dependents (cdr dependents)) (featurep dependv)) (if (yes-or-no-p (format "feature %s depends on %s ; unload %1$s?" dependv feature)) (load-manager-unload-feature dependv) (throw 'unable-to-unload "dependents still loaded")))) ;; else, it was a different error, so tell user about it: (apply #'error err))))) ;; this happens when the (feature-file feature) => nil (throw 'unable-to-unload (format "load-file of feature %s is not known" feature))))) ;(print features (current-buffer)) ;; test-case: ; (require 'bookmark) ;; requires pp , also ; (call-interactively #'load-manager-unload-feature) ; ;; now, try to make it unload pp ;; ;; it should work, but it's some ugly code that gets it to do so. ;; and it doesn't tell the user, yet, when a feature cannot be unloaded. ;; load-manager.el ends here