Re: [PATCH] Treat :tangle-mode as an octal value not integer

[Timothy <tecosaur@gmail.com>]

<tomas@tuxteam.de> writes:

> So you favour going the "full custom special parser". You're much more
> involved in Org, so I think your gut feeling counts more than mine here :)

Well, I'm not sure that my feeling is representative of experienced Org users,
my opinion basically boils down to:

>> I think as long as it’s clear what’s intended, and it’s not some home-baked
>> non-standard format, or terribly annoying to support — why not?

Rephrased: I think there are a few arguably "sensible" formats that a user could
reasonably assume, and if we can support most of them without introducing
ambiguity in parsing or interpretation (and I think we can), can't we make
everyone happy?

> `755' is the funniest one, since, strictly speaking it doesn't correspond
> to anything "out there" (note that the shell command `chmod' wants the
> leading zero, or, well, it will do surprising things if you don't
> provide it ;-)

Consider my suggestion amended to 0755 etc. :)

Anyway, as an example here's a code snippet that implements everything I've
mentioned.

#+begin_src emacs-lisp
(defvar org-tangle-default-mode #o544
  "The default mode for tangled files, as an integer.")

(defun org-interpret-file-mode (mode)
  (cond
   ((integerp mode) mode)
   ((not (stringp mode))
    (user-error "File mode %S not recognised as a valid format." mode))
   ((string-match-p "^0[0-7][0-7][0-7]$" mode)
    (string-to-number mode 8))
   ((string-match-p "^#o[0-7][0-7][0-7]$" mode)
    (string-to-number (substring mode 2) 8))
   ((string-match-p "^[ugoa]*\\(?:[+-=][rwxXstugo]*\\)+\\(,[ugoa]*\\(?:[+-=][rwxXstugo]*\\)+\\)*$" mode)
    (file-modes-symbolic-to-number mode 0))
   ((string-match-p "^[rwx-]\\{3\\}$" mode)
    (file-modes-symbolic-to-number (concat "u=" mode) org-tangle-default-mode))
   ((string-match-p "^[rwx-]\\{9\\}$" mode)
    (file-modes-symbolic-to-number (concat  "u=" (substring mode 0 3)
                                           ",g=" (substring mode 3 6)
                                           ",a=" (substring mode 6 9))
                                   org-tangle-default-mode))
   (t (user-error "File mode %S not recognised as a valid format." mode))))
#+end_src

--
Timothy