Re: [PATCH] Accept more :tangle-mode specification forms

[Max Nikulin]

On 05/10/2021 21:45, Timothy wrote:
> > Indeed, I’ve basically supported every form I could think of. I’m currently
> > inclined to cut it down to:
> > • 755
> > • “rwxrw-r–” (`ls -l’ style)
> > • chmod style with `org-babel-tangle-default-mode’ and 
> > `file-modes-symbolic-to-number’
> >
> > Maybe with (if anybody says they would like this)
> > • #o755 (elisp octal)
> > • 0755 (C octal)
> > • “rwx” = user perm, bit-or’d with `org-babel-tangle-default-mode’ for the rest
> >    (i.e. `org-babel-tangle-default-mode’, but not exceeding the user perm)

My opinion (discussion should not mean that I insist) is that since the 
following is currently working

#+begin_src bash :tangle yes :tangle-mode 755
  echo "Hello"
#+end_src

naked numbers (strings looking like numbers) should be forbidden. 
`org-lint' should report such lines and it should be at least warning 
for `org-babel-tagle'.

It is safer to define macros (namely macros, not just functions) that 
check argument type, e.g.

(filemode-octal "755") ; OK
(filemode-octal #o755) ; OK
(filemode-octal 755) ; Error

Maybe they should return not just raw number but e.g. tagged pair
(#o755 . 'filemode)

The point is that it should be hard to pass decimal or hex number 
(though it might be possible through a function generating tagged cons).

It is better to be a bit more verbose and explicit than to allow weird 
hard to notice later errors. Problem cases are too close to valid ones 
with current behavior.