Rails url to object reference

Hi all

Is there a quick utility to go from a url to an object reference, e.g.
http://rails/users/show/1@user, but not through a browser …?

I don’t want to access the object to look at it - I want the url string
itself to be interpreted - like for a wiki name in a wiki page

What would be best would be a function like:

return_object_ref(urlstring)

where urlstring = ‘http://rails/users/show/4’ or whatever.

Anyone know if such a thing exists?

Many thanks in advance

CHEERS> SAM