Re: regexp hell

[Filipp Gunbin <fgunbin@fastmail.fm>]

On 28/12/2012 10:57, B. T. Raven wrote:

> I am trying to byte-compile my .emacs for the first time and I see the
> complaint "replace-string is to be used interactively..." or something.
> I am using the form:
>
>   (replace-string "\\" "\\\\" nil (point-min) (point-max))
>
> in a function and it seems to work but I can't make any equivalent re's
> work in re-search-forward (the suggested equivalent  to be used in a
> lisp programm). I can't get past the "trailing backslash" error. Is
> there something kosher for the above replace-string form?
>
> Thanks,
>
> Ed
>

You can use `search-forward' (which searches for string, not for regexp),
as it is suggested in documentation for `replace-string':

  (while (search-forward FROM-STRING nil t)
    (replace-match TO-STRING nil t))

Then with the above strings it should replace one backslash with two.

But if you still need to write a regexp, it seems that you need to
double the amount of backslashes. To include a backslash in a regexp you
need to prefix it with another backslash and each backslash should be
prefixed with another one when written in a lisp program (so, 4
backslashes in a program for a single one in regexp).

-- 
Filipp Gunbin