[PATCH 1/7] emacs: Centralize notmuch command error handling

[Tomi Ollila]

On Sat, Dec 15 2012, Austin Clements <amdragon at MIT.EDU> wrote:

> This provides library functions for unified handling of errors from
> the notmuch CLI.  Follow-up patches will convert some scattered error
> handling to use this and add error handling where we currently ignore
> errors.
> ---

The series looks pretty good, some hardcoded patchs Mark noticed
and it looks to me (after viewing id:8738z7hd6x.fsf at qmul.ac.uk
that err -> nil could be done.

Would (goto-char (point-min)) be needed before (insert msg) in
this patch -- what If user has moved cursor while viewing old
error messages but not pressed q (dismissed) on the buffer. 
Also, what about (unless (eobp) (insert "\n")) to add empty
line between error messages ?

Tomi

>  emacs/notmuch-lib.el |   53 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 53 insertions(+)
>
> diff --git a/emacs/notmuch-lib.el b/emacs/notmuch-lib.el
> index 9c4ee71..851098f 100644
> --- a/emacs/notmuch-lib.el
> +++ b/emacs/notmuch-lib.el
> @@ -316,6 +316,59 @@ string), a property list of face attributes, or a list of these."
>  	(put-text-property pos next 'face (cons face cur))
>  	(setq pos next)))))
>  
> +(defun notmuch-pop-up-error (msg)
> +  "Pop up an error buffer displaying MSG.
> +
> +This will accumulate error messages in the errors buffer until
> +the user dismisses it."
> +
> +  (let ((buf (get-buffer-create "*Notmuch errors*")))
> +    (with-current-buffer buf
> +      (view-mode-enter nil #'kill-buffer)
> +      (let ((inhibit-read-only t))
> +	(insert msg)
> +	(unless (bolp)
> +	  (insert "\n"))
> +	(goto-char (point-min))))
> +    (pop-to-buffer buf)))
> +
> +(defun notmuch-check-exit-status (exit-status command &optional output err-file)
> +  "If EXIT-STATUS is non-zero, pop up an error buffer and signal an error.
> +
> +If EXIT-STATUS is non-zero, pop up a notmuch error buffer
> +describing the error and signal an Elisp error.  EXIT-STATUS must
> +be a number indicating the exit status code of a process or a
> +string describing the signal that terminated the process (such as
> +returned by `call-process').  COMMAND must be a list giving the
> +command and its arguments.  OUTPUT, if provided, is a string
> +giving the output of command.  ERR-FILE, if provided, is the name
> +of a file containing the error output of command.  OUTPUT and the
> +contents of ERR-FILE will be included in the error message."
> +
> +  ;; This is implemented as a cond to make it easy to expand.
> +  (cond
> +   ((eq exit-status 0) t)
> +   (t
> +    (notmuch-pop-up-error
> +     (concat
> +      (format "Error invoking notmuch.  %s exited with %s%s.\n"
> +	      (mapconcat #'identity command " ")
> +	      ;; Signal strings look like "Terminated", hence the
> +	      ;; colon.
> +	      (if (integerp exit-status) "status " "signal: ")
> +	      exit-status)
> +      (when err-file
> +	(concat "Error:\n"
> +		(with-temp-buffer
> +		  (insert-file-contents err-file)
> +		  (if (eobp)
> +		      "(no error output)\n"
> +		    (buffer-string)))))
> +      (when (and output (not (equal output "")))
> +	(format "Output:\n%s" output))))
> +    ;; Mimic `process-lines'
> +    (error "%s exited with status %s" (car command) exit-status))))
> +
>  ;; Compatibility functions for versions of emacs before emacs 23.
>  ;;
>  ;; Both functions here were copied from emacs 23 with the following copyright:
> -- 
> 1.7.10.4
>
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