Hi Tomi,

On Sun, Dec 20 2015, Tomi Ollila wrote:
> devel/try-emacs-mua provides an easy way to try and experiment
> with the notmuch emacs client distributed in emacs subdirectory of
> the notmuch source tree.
>
> try-emacs-mua starts a new emacs process and if initial checks pass
> *scratch* buffer is filled with information of how to begin.
>
> User can add normal emacs flags, like -q, -Q and e.g. -f notmuch. Any
> given plain filename arguments are filtered out (with message).

Why are plain files filtered? Yesterday, when I experimented with
jl-encrypt.el, I started emacs like:

  emacs -Q --directory ... --load notmuch.el /tmp/jl-encrypt.el

This allowed me to experiment with it (edebug), modify it and restart
emacs sessions easily without the need to type C-x C-f and the file name
in every session.

> If the emacs version in use is smaller than 24.4, special care is taken
> to ensure that notmuch*.elc files older than corresponding .el files
> are not loaded. Since emacs 24.4, setting `load-prefer-newer' variable
> takes care of this.
> ---
>
> Now all-elisp, vs v3: id:1447457397-11688-1-git-send-email-tomi.ollila@iki.fi
>
> In id:87si4bwrsu.fsf@qmul.ac.uk Mark had some thoughts if something from this
> could perhaps be used as some idea how to improve test testing. We'll have
> to think more of that later. Rest of the review is pretty much irrelevant
> for this (But I fixed that particular bug before turning to this ;).
>
>  devel/try-emacs-mua | 153 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 153 insertions(+)
>  create mode 100755 devel/try-emacs-mua
>
> diff --git a/devel/try-emacs-mua b/devel/try-emacs-mua
> new file mode 100755
> index 000000000000..1f916d2806f9
> --- /dev/null
> +++ b/devel/try-emacs-mua
> @@ -0,0 +1,153 @@
> +#!/bin/sh
> +:; set -x; exec "${EMACS:-emacs}" --debug-init --load "$0" "$@"; exit

Huh! Nice trick, especially the ":;" :)

> +;;
> +;; Try the notmuch emacs client located in ../notmuch/emacs directory
> +;;
> +;; Run this without arguments; emacs window opens with some usage information
> +;;
> +;; Authors: Tomi Ollila <tomi.ollila@iki.fi>
> +;;
> +;; http://www.emacswiki.org/emacs/EmacsScripts was a useful starting point...
> +;;
> +;; Licence: GPLv3+
> +;;
> +
> +(message "Starting '%s'" load-file-name)
> +
> +(set-buffer "*scratch*")
> +
> +(setq initial-buffer-choice t) ;; *scratch* buffer
> +
> +(when (featurep 'notmuch)
> +  (insert "
> +Notmuch has been loaded to this emacs (during processing of the init file)
> +which means it is (most probably) loaded from different source than expected.
> +
> +Please run \"" (file-name-nondirectory load-file-name)
> +"\" with '-q' (or '-Q') as an argument, to disable
> +processing of the init file -- you can load it after emacs has started\n
> +exit emacs (y or n)? ")
> +  (if (y-or-n-p "exit emacs")
> +      (kill-emacs)
> +    (error "Stopped reading %s" load-file-name)))
> +
> +(let ((pdir (file-name-directory
> +	     (directory-file-name (file-name-directory load-file-name)))))
> +  (unless (file-exists-p (concat pdir "emacs/notmuch-lib.el"))
> +    (insert "Cannot find notmuch-emacs source directory
> +while looking at: " pdir "emacs\n\nexit emacs (y or n)? ")
> +    (if (y-or-n-p "exit emacs")
> +	(kill-emacs)
> +      (error "Stopped reading %s" load-file-name)))
> +  (setq try-notmuch-source-directory (directory-file-name pdir))
> +  (setq try-notmuch-emacs-directory (concat pdir "emacs/"))
> +  (setq load-path (cons try-notmuch-emacs-directory load-path)))
> +
> +;; for logging, debugging and load tracing (broke on emacs 24.5.1 :O)
> +;;(defadvice file-truename (before before-file-truename activate)
> +;;;;  (message "file-truename: '%s' '%s' '%s'" filename counter prev-dirs))
> +;;  (unless counter
> +;;    (message "file-truename: %s" filename)))

What is the benefit of advising file-truename? Especially when you do
other type of logging below. I'd prefer to have this as a comment in the
file. Or is this some leftover from your experiments?

> +
> +;; they say advice doesn't work for primitives (functions from c source)
> +;; well, these 'before' advice works for emacs 23.1 - 24.5 (at least)
> +;; ...and for our purposes 24.3 is enough (there is no load-prefer-newer there)
> +;; note also that the old, "obsolete" defadvice mechanism was used, but that
> +;; is the only one available for emacs 23 and 24 up to 24.3.
> +
> +(if (boundp 'load-prefer-newer)
> +    (defadvice require (before before-require activate)
> +      (unless (featurep feature)
> +	(message "require: %s" feature)))
> +  ;; else: special require "short-circuit"; after load feature is provided...
> +  ;; ... in notmuch sources we always use require and there are no loops
> +  (defadvice require (before before-require activate)
> +    (unless (featurep feature)
> +      (message "require: %s" feature)
> +      (let ((name (symbol-name feature)))
> +	(if (and (string-match "^notmuch" name)
> +		 (file-newer-than-file-p
> +		  (concat try-notmuch-emacs-directory name ".el")
> +		  (concat try-notmuch-emacs-directory name ".elc")))
> +	    (load (concat try-notmuch-emacs-directory name ".el") nil nil t t)
> +	  )))))
> +
> +(insert "Found notmuch emacs client in " try-notmuch-emacs-directory "\n")
> +
> +(condition-case err
> +;; "opportunistic" load-prefer-newer -- will be effective since emacs 24.4
> +    (let ((load-prefer-newer t)
> +	  (force-load-messages t))
> +      (require 'notmuch))
> +  ;; specifying `debug' here lets the debugger run
> +  ;; if `debug-on-error' is non-nil.
> +  ((debug error)
> +   (progn
> +     (insert "\nLoading notmuch failed: " (error-message-string err) "\n")
> +     (insert "See *Messages* buffer for more information.\n")
> +     (error "Stopped reading %s" load-file-name))))
> +
> +(insert "
> +Go to the end of the following lines and type C-x C-e to evaluate
> +(or C-j which is shorter but inserts evaluation results into buffer)
> +
> +To \"disable\" mail sending, evaluate
> +* (setq message-send-mail-function (lambda () t))
> +")
> +
> +(if (file-exists-p (concat try-notmuch-source-directory "/notmuch"))
> +    (insert "
> +To use accompanied notmuch binary from the same source, evaluate
> +* (setq exec-path (cons \"" try-notmuch-source-directory  "\" exec-path))
> +Note: Evaluating the above may be followed by unintended database
> +upgrade and getting back to old version may require dump & restore.
> +"))

You can also inform the user which notmuch binary will be used without
the above setq.

> +
> +(if init-file-user ;; nil, if '-q' or '-Q' is given, but no '-u' 'USER'
> +    (insert "
> +Your init file was processed during emacs startup. If you want to test
> +notmuch emacs mail client without your emacs init file interfering, Run\n\""
> +(file-name-nondirectory load-file-name) "\" with '-q' (or '-Q') as an argument.
> +")
> +  (let ((init-file-name))
> +    ;; determining init file name in startup.el/command-line is too complicated
> +    ;; to be duplicated here; these 3 file names covers most of the users
> +    (mapc (lambda (fn) (if (file-exists-p fn) (setq init-file-name fn)))
> +	  '("~/.emacs.d/init.el" "~/.emacs" "~/.emacs.el"))
> +    (if init-file-name
> +	(insert "
> +If you want to load your emacs init file now, evaluate
> +* (load \"" init-file-name "\")
> +")))
> +  (insert "
> +If you want to use packages (e.g. company from elpa) evaluate
> +* (progn (require 'package) (package-initialize))
> +"))
> +
> +(insert "
> +To start notmuch (hello) screen, evaluate
> +* (notmuch-hello)")
> +
> +(setq try-emacs-pop-messages-buffers nil)

If this variable was named something like arg-ignored, the code bellow
would be easier to understand.

> +(add-hook 'command-line-functions
> +	  (lambda ()
> +	    (unless try-emacs-pop-messages-buffers (message "%s" ""))
> +	    (message "*** Ignoring arg '%s'" argi)
> +	    (setq try-emacs-pop-messages-buffers t)))
> +
> +(add-hook 'emacs-startup-hook
> +	  (lambda ()
> +	    (when try-emacs-pop-messages-buffers
> +	      (message "%s" "")
> +	      (message "Press 'q' to hide this window")

Pressing 'q' doesn't work under Emacs 23.

> +	      (pop-to-buffer "*Messages*"))
> +	    (set-buffer "*scratch*")
> +	    (lisp-interaction-mode)
> +	    (goto-char (point-min))
> +	    (forward-line)
> +	    (set-buffer-modified-p nil)))
> +
> +;; Local Variables:
> +;; mode: emacs-lisp
> +;; End:

-Michal