Could I have some commentary on this? I think the mechanism for changing defaults based on packages’ presence is reasonable, but there is a penalty at startup, which makes me consider caching path and file presence information in a file in ~/.xemacs/ and comparing timestamps on startup before re-initialising it on every startup. lisp/ChangeLog addition: 2005-03-20 Aidan Kehoe <kehoea(a)parhasard.net&gt; * menubar-items.el (default-menubar): Add an entry for VM, rename the entry for sendmail-user-agent to better describe it. * packages.el (package-presence-default-tweaks): New. List of libraries and functions to be called with information on their presence at startup. * simple.el (mail-user-agent): Update the docstring and Customize init information to mention VM. * simple.el (packages): Require it. * simple.el (initialize-mua-to-vm-if-available): New. Function that initializes mail-user-agent to 'vm-user-agent if the VM package is available. * simple.el ('vm-user-agent): New. Previously available in the VM package. * startup.el (normal-top-level): Loop through package-presence-default-tweaks, looking for the library specified in the car of each element, and calling the function specified as the second slot of that element with the result of that lookup. man/ChangeLog addition: 2005-03-20 Aidan Kehoe <kehoea(a)parhasard.net&gt; * xemacs/sending.texi (Sending Mail): Describe that we've changed the default to VM, cross reference to its docs. 2005-03-20 Aidan Kehoe <kehoea(a)parhasard.net&gt; * lispref/packaging.texi (Dumped defaults): Describe and cross reference the package-presence-default-tweaks. XEmacs Trunk source patch: Diff command: cvs -q diff -u Files affected: man/xemacs/sending.texi man/lispref/packaging.texi lisp/startup.el lisp/simple.el lisp/packages.el lisp/menubar-items.el Index: lisp/menubar-items.el =================================================================== RCS file: /pack/xemacscvs/XEmacs/xemacs/lisp/menubar-items.el,v retrieving revision 1.46 diff -u -u -r1.46 menubar-items.el --- lisp/menubar-items.el 2005/02/03 05:03:38 1.46 +++ lisp/menubar-items.el 2005/03/20 11:35:57 ＠＠ -886,7 +886,11 ＠＠ :active (boundp 'ps-print-color-p)]) ("%_Internet" ("%_Compose Mail With" - ["Default Emacs Mailer" + ["VM mail package" + (customize-set-variable 'mail-user-agent 'vm-user-agent) + :style radio + :selected (eq mail-user-agent 'vm-user-agent)] + ["Bare-bones Emacs Mailer" (customize-set-variable 'mail-user-agent 'sendmail-user-agent) :style radio :selected (eq mail-user-agent 'sendmail-user-agent)] Index: lisp/packages.el =================================================================== RCS file: /pack/xemacscvs/XEmacs/xemacs/lisp/packages.el,v retrieving revision 1.53 diff -u -u -r1.53 packages.el --- lisp/packages.el 2005/02/03 23:56:53 1.53 +++ lisp/packages.el 2005/03/20 11:35:57 ＠＠ -518,6 +518,19 ＠＠ package-load-path) (reverse *files*))) +(defvar package-presence-default-tweaks nil + "Library names and functions to call with their presence, on startup. +A list of lists, of the form: + + '((\"library-name\" 'function)) + +Before the user's initialization files are loaded, but after the packages +load path has been worked out, XEmacs calls `(locate-library +\"library-name\")', and passes its result to `function', for each element of +`package-presence-default-tweaks'. The intention is that `function' +initializes some, dumped, XEmacs default based on the runtime presence of +some package. ") + (provide 'packages) ;;; packages.el ends here Index: lisp/simple.el =================================================================== RCS file: /pack/xemacscvs/XEmacs/xemacs/lisp/simple.el,v retrieving revision 1.50 diff -u -u -r1.50 simple.el --- lisp/simple.el 2005/02/23 22:25:16 1.50 +++ lisp/simple.el 2005/03/20 11:36:01 ＠＠ -3312,10 +3312,14 ＠＠ outgoing email message. This variable lets you specify which mail-sending package you prefer. -Valid values include: - - `sendmail-user-agent' -- use the default Emacs Mail package. - See Info node `(emacs)Sending Mail'. +Valid values may include: + + `vm-user-agent' -- use Kyle Jones' VM, as documented in the `(vm)' + Info node. Compatible with `sendmail-user-agent' + and can handle attachments and non-ASCII content, + which the former can't. + `sendmail-user-agent' -- use the former preferred, bare-bones, Emacs Mail + package. See Info node `(xemacs)Sending Mail'. `mh-e-user-agent' -- use the Emacs interface to the MH mail system. See Info node `(mh-e)'. `message-user-agent' -- use the Gnus Message package. ＠＠ -3329,7 +3333,10 ＠＠ succeeds. See also `read-mail-command' concerning reading mail." -:type '(radio (function-item :tag "Default Emacs mail" +:type '(radio (function-item :tag "VM mail package" + :format "%t\n" + vm-user-agent) + (function-item :tag "Bare-bones Emacs mail" :format "%t\n" sendmail-user-agent) (function-item :tag "Emacs interface to MH" ＠＠ -3344,6 +3351,19 ＠＠ (function :tag "Other")) :group 'mail) +(require 'packages) + +;; VM's composition package is compatible with sendmail-user-agent, and it +;; supports MIME, so we should prefer it as a default if it's available. +(defun initialize-mua-to-vm-if-available (path) + "If `path' is non-nil, make VM be XEmacs' default `mail-user-agent'. +This should be called from `startup.el' by means of the +`package-presence-default-tweaks' mechanism. " + (when path (setq mail-user-agent 'vm-user-agent))) + +(pushnew '("vm" initialize-mua-to-vm-if-available) + package-presence-default-tweaks) + (defun define-mail-user-agent (symbol composefunc sendfunc &optional abortfunc hookvar) "Define a symbol to identify a mail-sending package for `mail-user-agent'. ＠＠ -3385,6 +3405,12 ＠＠ (define-mail-user-agent 'message-user-agent 'message-mail 'message-send-and-exit 'message-kill-buffer 'message-send-hook) + +(define-mail-user-agent 'vm-user-agent + (function vm-compose-mail) ; compose function + (function vm-mail-send-and-exit) ; send function + nil ; abort function (kill-buffer) + nil) ; hook variable (mail-send-hook) (defun rfc822-goto-eoh () ;; Go to header delimiter line in a mail message, following RFC822 rules Index: lisp/startup.el =================================================================== RCS file: /pack/xemacscvs/XEmacs/xemacs/lisp/startup.el,v retrieving revision 1.53 diff -u -u -r1.53 startup.el --- lisp/startup.el 2005/01/26 04:56:18 1.53 +++ lisp/startup.el 2005/03/20 11:36:02 ＠＠ -562,6 +562,13 ＠＠ auto-save-list-file-prefix (emacs-pid) (system-name))))) + ;; Some of XEmacs' default settings--initially the mail composition + ;; agent--depend on the presence of a given package at startup. + (require 'packages) + (dolist (lib-presence package-presence-default-tweaks) + (apply (second lib-presence) + (locate-library (car lib-presence)) + nil)) (run-hooks 'emacs-startup-hook) (and term-setup-hook (run-hooks 'term-setup-hook)) Index: man/lispref/packaging.texi =================================================================== RCS file: /pack/xemacscvs/XEmacs/xemacs/man/lispref/packaging.texi,v retrieving revision 1.11 diff -u -u -r1.11 packaging.texi --- man/lispref/packaging.texi 2003/10/10 12:39:34 1.11 +++ man/lispref/packaging.texi 2005/03/20 11:36:03 ＠＠ -61,6 +61,7 ＠＠ ＠c * Frequently Asked Questions:: Questions and answers from the mailing list. Internals and Package Release Engineering: +* Dumped defaults:: Dumped code can check for packages. * Issues:: ＠end menu ＠＠ -1322,7 +1323,7 ＠＠ directory, then an entry in ＠code{package-name-to-directory} is also necessary, or requires will fail, leading to the problems just described. -＠node Documenting Packages, Issues, Creating Packages, Packaging +＠node Documenting Packages, Dumped defaults, Creating Packages, Packaging ＠comment node-name, next, previous, up ＠cindex documenting packages ＠heading Documenting Packages: ＠＠ -1357,7 +1358,26 ＠＠ Do maintain a detailed ChangeLog. -＠node Issues, , Documenting Packages, Packaging +＠node Dumped defaults, Issues, Documenting Packages, Packaging +＠section Dumped defaults + +Since the best options for many defaults within XEmacs involve packages +that are not necessarily present at runtime, we provide a mechanism for +dumped code to check for packages' presence at startup and to initialize +these defaults as appropriate. + +This is accomplished using ＠code{package-presence-default-tweaks}, +defined in ＠file{lisp/packages.el}. This is a list of lists, with the +first element of each entry the name of a Lisp library to be checked +for, and the second element a function symbol to be called with the +result of ＠code{locate-library} on the Lisp library. These checks are +done after the packages load path is initialized. + +See the documentation for ＠code{package-presence-default-tweaks}, and +the check for the presence of VM and consequent default mailer change in +(a)file{lisp/simple.el}. + +＠node Issues, , Dumped defaults, Packaging ＠section Issues To be completed. Index: man/xemacs/sending.texi =================================================================== RCS file: /pack/xemacscvs/XEmacs/xemacs/man/xemacs/sending.texi,v retrieving revision 1.4 diff -u -u -r1.4 sending.texi --- man/xemacs/sending.texi 2001/04/12 18:22:30 1.4 +++ man/xemacs/sending.texi 2005/03/20 11:36:04 ＠＠ -40,6 +40,16 ＠＠ ＠kbd{C-u C-x m} is another way to switch back to a message in progress: it will search for an existing, unsent mail message buffer and select it. +Starting with version 21.5, the default mail composition package in +XEmacs is VM, which is compatible with `sendmail.el' (the old default, +as described in this document) and has thorough support for attachments +and non-ASCII messages. ＠xref{(vm)}, for the full VM documentation, +should you want information on these features. XEmacs' package system +can mean that VM isn't installed---in that case, `sendmail.el' will +be the fallback. If your mail buffer is called ``*mail*'', then +you probably don't have VM installed; ＠pxref{Packages} for information +on how to install the package. + ＠menu * Format: Mail Format. Format of the mail being composed. * Headers: Mail Headers. Details of allowed mail header fields. cvs server: cannot find modules/ldap/configure -- “I, for instance, am gung-ho about open source because my family is being held hostage in Rob Malda’s basement. But who fact-checks me, or Enderle, when we say something in public? No-one!” -- Danny O’Brien