Re: [O] Chaining strings between babel blocks: why so many '\'?

[Nicolas Goaziou]

Hello,

Alan Schmitt <address@hidden> writes:

> I've been playing with block chaining to generate some dot file then to
> export then as images. I had a little trouble finding the number of '\'
> I need to put in front of a quote if I want the quote to be quoted. Here
> is a way to make it work:
>
> #+name: foo
> #+begin_src emacs-lisp :exports none
> "bar [label = \"\\\\\"test1\\\\\"\"]\nbaz [label = \"\\\\\"test2\\\\\"\"]"
> #+end_src
>
> #+results: foo
> : bar [label = "\\"test1\\""]
> : baz [label = "\\"test2\\""]
>
> #+begin_src dot :file ~/tmp/test-dot.png :var input=foo :exports results
> graph {
>   $input
> }
> #+end_src
>
> My question is: why can't I simply use this:
>
> #+name: foo
> #+begin_src emacs-lisp :exports none
> "bar [label = \"\\\"test1\\\"\"]\nbaz [label = \"\\\"test2\\\"\"]"
> #+end_src
>
> #+results: foo
> : bar [label = "\"test1\""]
> : baz [label = "\"test2\""]
>
> (I guess the answer is in the error in replace-regexp-in-string:
> (error "Invalid use of `\\' in replacement text")
> .)

Indeed. This function, unless told not to, treats backslashes characters
specially.

> Would it be problematic to first transform every "\\" into a "\\\\" in
> org-babel-expand-body:dot, before the call to
> replace-regexp-in-string?

I think `replace-regexp-in-string' should be called with a non-nil
LITERAL argument in this case.


Regards,

-- 
Nicolas Goaziou