regexp hell

regexp hell

[B. T. Raven]

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

Re: regexp hell

[Filipp Gunbin]

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

Re: regexp hell

[B. T. Raven]

> 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.

Thanks, Filipp. That's what I needed. Now the .emacs byte-compiles
without issuing a warning.


> 
> 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).
>