Re: master ca47390: image-dired: Report when a necessary executable is not found

[Tino Calancha <tino.calancha@gmail.com>]

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On Mon, 5 Sep 2016, Clément Pit--Claudel wrote:

>Looks good, but maybe you could extract this to a separate function that 
>takes the variable name and produces the error?  There's a bit of 
> duplication in the patch you posted.
Thanks for your help.
Sure, how about this new patch?
It reverts ca473907, so that the options storing the executable names are
never nil, i.e., there is no need to reset the options after installing
the missing executables.

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From 37a295e7149b459ea1cccfbf0ce49c5a50676a52 Mon Sep 17 00:00:00 2001
From: Tino Calancha <tino.calancha@gmail.com>
Date: Tue, 6 Sep 2016 02:50:56 +0900
Subject: [PATCH] image-dired: Signal an error before calling a missing
  executable

Reverts commit ca473907
* lisp/image-dired.el (image-dired--check-executable-exists): New defun.
Throw and error when the executable arg is missing.
(image-dired-display-image, image-dired-rotate-thumbnail)
(image-dired-rotate-original, image-dired-set-exif-data)
(image-dired-get-exif-data):
Use it.
---
  lisp/image-dired.el | 48 +++++++++++++++++++++++-------------------------
  1 file changed, 23 insertions(+), 25 deletions(-)

diff --git a/lisp/image-dired.el b/lisp/image-dired.el
index 5ac4600..07f66e0 100644
--- a/lisp/image-dired.el
+++ b/lisp/image-dired.el
@@ -224,7 +224,7 @@ image-dired-gallery-thumb-image-root-url
    :group 'image-dired)

  (defcustom image-dired-cmd-create-thumbnail-program
-  (executable-find "convert")
+  "convert"
    "Executable used to create thumbnail.
  Used together with `image-dired-cmd-create-thumbnail-options'."
    :type 'string
@@ -242,7 +242,7 @@ image-dired-cmd-create-thumbnail-options
    :group 'image-dired)

  (defcustom image-dired-cmd-create-temp-image-program
-  (executable-find "convert")
+  "convert"
    "Executable used to create temporary image.
  Used together with `image-dired-cmd-create-temp-image-options'."
    :type 'string
@@ -308,7 +308,7 @@ image-dired-cmd-create-standard-thumbnail-command
    :group 'image-dired)

  (defcustom image-dired-cmd-rotate-thumbnail-program
-  (executable-find "mogrify")
+  "mogrify"
    "Executable used to rotate thumbnail.
  Used together with `image-dired-cmd-rotate-thumbnail-options'."
    :type 'string
@@ -326,20 +326,14 @@ image-dired-cmd-rotate-thumbnail-options
    :group 'image-dired)

  (defcustom image-dired-cmd-rotate-original-program
-  (cond ((executable-find "jpegtran"))
-        ((executable-find "convert")))
+  "jpegtran"
    "Executable used to rotate original image.
  Used together with `image-dired-cmd-rotate-original-options'."
    :type 'string
    :group 'image-dired)

  (defcustom image-dired-cmd-rotate-original-options
-  (when image-dired-cmd-rotate-original-program
-    (pcase image-dired-cmd-rotate-original-program
-      ((pred (lambda (x) (string-match-p "jpegtran" x)))
-       "%p -rotate %d -copy all -outfile %t \"%o\"")
-      ((pred (lambda (x) (string-match-p "convert" x)))
-       "%p -rotate %d \"%o\" %t")))
+  "%p -rotate %d -copy all -outfile %t \"%o\""
    "Format of command used to rotate original image.
  Available options are %p which is replaced by
  `image-dired-cmd-rotate-original-program', %d which is replaced by the
@@ -364,7 +358,7 @@ image-dired-rotate-original-ask-before-overwrite
    :group 'image-dired)

  (defcustom image-dired-cmd-write-exif-data-program
-  (executable-find "exiftool")
+  "exiftool"
    "Program used to write EXIF data to image.
  Used together with `image-dired-cmd-write-exif-data-options'."
    :type 'string
@@ -381,7 +375,7 @@ image-dired-cmd-write-exif-data-options
    :group 'image-dired)

  (defcustom image-dired-cmd-read-exif-data-program
-  (executable-find "exiftool")
+  "exiftool"
    "Program used to read EXIF data to image.
  Used together with `image-dired-cmd-read-exif-data-program-options'."
    :type 'string
@@ -619,10 +613,14 @@ image-dired-thumb-name
                     (file-name-base f)
                     (file-name-extension f))))))

+(defun image-dired--check-executable-exists (executable)
+  (unless (executable-find (symbol-value executable))
+    (error "Executable %S not found" executable)))
+
  (defun image-dired-create-thumb (original-file thumbnail-file)
    "For ORIGINAL-FILE, create thumbnail image named THUMBNAIL-FILE."
-  (unless image-dired-cmd-create-thumbnail-program
-    (error "image-dired-cmd-create-thumbnail-program is nil"))
+  (image-dired--check-executable-exists
+   'image-dired-cmd-create-thumbnail-program)
    (let* ((width (int-to-string image-dired-thumb-width))
           (height (int-to-string image-dired-thumb-height))
           (modif-time (format "%.0f" (float-time (nth 5 (file-attributes
@@ -1820,8 +1818,8 @@ image-dired-display-image
          (progn
            (setq width (image-dired-display-window-width))
            (setq height (image-dired-display-window-height))
-          (unless image-dired-cmd-create-temp-image-program
-            (error "image-dired-cmd-create-temp-image-program is nil"))
+          (image-dired--check-executable-exists
+           'image-dired-cmd-create-temp-image-program)
            (setq command
                  (format-spec
                   image-dired-cmd-create-temp-image-options
@@ -1878,8 +1876,8 @@ image-dired-image-at-point-p

  (defun image-dired-rotate-thumbnail (degrees)
    "Rotate thumbnail DEGREES degrees."
-  (unless image-dired-cmd-rotate-thumbnail-program
-    (error "image-dired-cmd-rotate-thumbnail-program is nil"))
+  (image-dired--check-executable-exists
+   'image-dired-cmd-rotate-thumbnail-program)
    (if (not (image-dired-image-at-point-p))
        (message "No thumbnail at point")
      (let ((file (image-dired-thumb-name 
(image-dired-original-file-name)))
@@ -1924,8 +1922,8 @@ image-dired-rotate-original
    "Rotate original image DEGREES degrees."
    (unless (image-dired-image-at-point-p)
      (message "No image at point"))
-  (unless image-dired-cmd-rotate-original-program
-    (error "image-dired-cmd-rotate-original-program is nil"))
+  (image-dired--check-executable-exists
+   'image-dired-cmd-rotate-original-program)
    (let ((file (image-dired-original-file-name))
          command)
      (unless (eq 'jpeg (image-type file))
@@ -2002,8 +2000,8 @@ image-dired-thumbnail-set-image-description

  (defun image-dired-set-exif-data (file tag-name tag-value)
    "In FILE, set EXIF tag TAG-NAME to value TAG-VALUE."
-  (unless image-dired-cmd-write-exif-data-program
-    (error "image-dired-cmd-write-exif-data-program is nil"))
+  (image-dired--check-executable-exists
+   'image-dired-cmd-write-exif-data-program)
    (let (command)
      (setq command (format-spec
                     image-dired-cmd-write-exif-data-options
@@ -2016,8 +2014,8 @@ image-dired-set-exif-data

  (defun image-dired-get-exif-data (file tag-name)
    "From FILE, return EXIF tag TAG-NAME."
-  (unless image-dired-cmd-read-exif-data-program
-    (error "image-dired-cmd-read-exif-data-program is nil"))
+  (image-dired--check-executable-exists
+   'image-dired-cmd-read-exif-data-program)
    (let ((buf (get-buffer-create "*image-dired-get-exif-data*"))
          command tag-value)
      (setq command (format-spec
-- 
2.9.3

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Repository revision: 62e4dc4660cb3b29cfffcad0639e51c7f382ced8