bind-string-match: comments please

bind-string-match: comments please

[weber]

I've written this helper function:

(defun bind-string-match (regexp string &optional start)
  (let ((ret (string-match regexp string start)))
	(when ret
	  (catch 'end
		(dolist (i (number-sequence 1 10))
		  (let ((match (match-string i string)))
			(if match
				(eval `(setq ,(intern (concat "$" (number-to-string i))) ,match))
				(throw 'end t))))))
	ret))

so that I can access the match groups with $1.. instead of (match-
string 1 string).
Is there any recommendation against this type of functions? Other than
polluting the global namespace?
Also, can one rewrite it without the `eval'?

TIA,
weber

PS: I'm not a Perl programmer!

Re: bind-string-match: comments please

[Andreas Politz]

weber wrote:
> I've written this helper function:
> 
> (defun bind-string-match (regexp string &optional start)
>   (let ((ret (string-match regexp string start)))
> 	(when ret
> 	  (catch 'end
> 		(dolist (i (number-sequence 1 10))
> 		  (let ((match (match-string i string)))
> 			(if match
> 				(eval `(setq ,(intern (concat "$" (number-to-string i))) ,match))
> 				(throw 'end t))))))
> 	ret))
> 
> so that I can access the match groups with $1.. instead of (match-
> string 1 string).
> Is there any recommendation against this type of functions? Other than
> polluting the global namespace?

I think sooner or later you get into trouble, if you don't clear
the match variables. They could still hold values from 10 matches
ago, while the current regexp doesn't match at all.
> Also, can one rewrite it without the `eval'?

The 'q' in setq stands for quoted. So, just using set should
work.
> 
> TIA,
> weber
> 
> PS: I'm not a Perl programmer!

Maybe what you really want is some kind of macro ?

(defmacro with-string-matches (string &rest body)
   `(let ,(mapcar (lambda (submatch)
		     (list (intern (format "$%d" submatch))
			   (match-string submatch (eval string))))
		(number-sequence 0 10))
      ,@body))


(let ((str "abbbbc") idx)
   (setq idx (string-match "a\\(b+\\)c" str))
   (with-string-matches str
     (message "%s %s" $0 $1)))


-ap

Re: bind-string-match: comments please

[weber]

On 30 set, 15:30, Andreas Politz <poli...@fh-trier.de> wrote:
> weber wrote:
> > I've written this helper function:
>
> > (defun bind-string-match (regexp string &optional start)
> >   (let ((ret (string-match regexp string start)))
> >    (when ret
> >      (catch 'end
> >            (dolist (i (number-sequence 1 10))
> >              (let ((match (match-string i string)))
> >                    (if match
> >                            (eval `(setq ,(intern (concat "$" (number-to-string i))) ,match))
> >                            (throw 'end t))))))
> >    ret))
>
> > so that I can access the match groups with $1.. instead of (match-
> > string 1 string).
> > Is there any recommendation against this type of functions? Other than
> > polluting the global namespace?
>
> I think sooner or later you get into trouble, if you don't clear
> the match variables. They could still hold values from 10 matches
> ago, while the current regexp doesn't match at all.
>
> > Also, can one rewrite it without the `eval'?
>
> The 'q' in setq stands for quoted. So, just using set should
> work.
>
>
>
> > TIA,
> > weber
>
> > PS: I'm not a Perl programmer!
>
> Maybe what you really want is some kind of macro ?
>
> (defmacro with-string-matches (string &rest body)
>    `(let ,(mapcar (lambda (submatch)
>                      (list (intern (format "$%d" submatch))
>                            (match-string submatch (eval string))))
>                 (number-sequence 0 10))
>       ,@body))
>
> (let ((str "abbbbc") idx)
>    (setq idx (string-match "a\\(b+\\)c" str))
>    (with-string-matches str
>      (message "%s %s" $0 $1)))
>
> -ap

Yeah, I was drifting that way after recalling pg's anaphoric
macros....
Thanks a lot :)
-weber