Re: rx vs sregex - a "match" to the death

[Oliver Scholz <alkibiades@gmx.de>]

Martin Stone Davis <m0davis@pacbell.net> writes:
[...]
> While I was comparing the two functions, I could not find if/how rx
> handles numbered backreferences.  It's done in sregex like this:
>
> ;;   (sregexq (group (or "Go" "Run"))
> ;;            ", Spot, "
> ;;            (backref 1))             =>  "\\(Go\\|Run\\), Spot, \\1"
>
> How do you do the same using rx?
[...]

Well, you could use (regexp "\\1"), but this is of course not
satisfying. I am not aware of any other way to use backrefs with `rx'.

However, I was not aware that you actually can use backrefs within a
regexp. I tried 

(progn (looking-at "\\w+")
       (forward-char 1)
       (re-search-forward "\\0" nil t))

But that did not lead to the result that you would expect if backrefs
are/were supported within regexps.

Could you provide an example where this is meaningful?

    Oliver
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