Re: [RFC] Org version of the Org manual

[Nicolas Goaziou <n.goaziou@gmail.com>]

Hello,

Achim Gratz <Stromeko@Nexgo.DE> writes:

> Am 21.03.2013 22:02, schrieb Nicolas Goaziou:
>> I suggest the following code instead, which allows to escape the
>> escaping backslash so the comma is not escaped:
>>
>>    (args (mapcar 'org-trim
>>                  (split-string
>>                   (replace-regexp-in-string
>>                    "\\(\\\\+\\)?\\(,\\)"
>>                    (lambda (str)
>>                      (let ((slashes (match-string 1 str)))
>>                        (if (or (not slashes) (evenp (length slashes))) "\\1\000"
>>                          (concat (make-string (1- (length slashes)) ?\\) ","))))
>>                    (org-match-string-no-properties 3))
>>                   "\000")))
>>
>> What do you think about it?
>
> I think this is a lot harder to understand

Actually it is harder to understand because it doesn't make any sense:
the code is wrong. More on this below.

> and I would guess it is also quite a bit slower.

Speed difference is not significant here.

> Also I'm not sure why you are trying to match multiple backslashes.
> The original implementation and the description of the syntax says
> that the only character that can be escaped is a comma, so the new
> implementation changes behaviour in that regard (maybe intentionally,
> I can't tell).

Actually the code I pasted is wrong, I meant:

  (split-string
   (replace-regexp-in-string
    "\\(\\\\+\\)?\\(,\\)"
    (lambda (str)
      (let ((len (length (match-string 1 str))))
        (if (evenp len) (concat (make-string (/ len 2) ?\\) "\000")
          (concat (make-string (/ (1- len) 2) ?\\) ","))))
    (org-matcĥ-string-no-properties 3) nil t)
   "\000")

With the current implementation (and in your refactoring), it is
impossible to have '("a\,b").

If you allow to escape a character, you should also be able to escape
the escaping character. With this patch:

  "a,b"     -> '("a" "b")
  "a\,b"    -> '("a,b")
  "a\\,b"   -> '("a\" "b")
  "a\\\,b"  -> '("a\,b")
  "a\\\\,b" -> '(a"\\" "b")

Note that with the patch, you only need to escape backslashes before
a comma:

  "a\\b\,c" -> '("a\\b,c")

If consistency is a matter, a slightly different patch can require to
escape every backslash character. Though, I don't think it is necessary.


Regards,

-- 
Nicolas Goaziou