# Railsy Question about redefining ruby methods **URL:** \ **Category:** Ruby\ **Created:** [May 24, 2008, 4:11am UTC](https://www.ruby-forum.com/t/railsy-question-about-redefining-ruby-methods/138533 "2008-05-24T04:11:36Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Xeno\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/x/958977/32.png) [@Xeno\_C](https://www.ruby-forum.com/u/Xeno_C)\ **Post date:** [May 24, 2008, 4:11am UTC](https://www.ruby-forum.com/t/railsy-question-about-redefining-ruby-methods/138533/1 "2008-05-24T04:11:36Z")
Please this is a Ruby question, not, at least as the main focus, a rails one, as you’ll see if you read all the way through. Say, I’ve got a case in Rails where I want all my links to be prepended with something like ~u1/rrsw/thingies so I can see [http://host/~u1/rrsw/thingies](http://host/~u1/rrsw/thingies) and [http://host/~u2/rrsw/thingies](http://host/~u2/rrsw/thingies) instead of [http://host:9001/thingies](http://host:9001/thingies) and [http://host:9002/thingies](http://host:9002/thingies) for a rails tool that is used by some n projects. The rails part is apparently not configurable, so I’m looking at redefining rails methods like link\_to to stick the path in there. This should be reasonable, but I’m stuck on a ruby problem: I want to redefine the link\_to method so it’s seen in its new guise in all the places where it’s presently used. It seems to make most sense to put the new redefinition in the module ApplicationHelpers, but I believe that may short circuit the access, as I’m not seeing the example I put in which always puts out a traceable constant, resulting in the expected changes in my test web pages. So, and here is the question: Can anyone suggest how I should specify an appropriately available method for the correct module inside another module so that it overrides the original in the fashion I desire? I presume this is a simple problem, as it’s what people do all the time in OO right? I’m still a little green on these patterns yet I think. Thanks for any suggestions. Sincerely, Xeno C. Droopy hacker on a Friday Evening… ---
**Author:** ![Xeno\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/x/958977/32.png) [@Xeno\_C](https://www.ruby-forum.com/u/Xeno_C)\ **Post date:** [May 24, 2008, 8:11am UTC](https://www.ruby-forum.com/t/railsy-question-about-redefining-ruby-methods/138533/2 "2008-05-24T08:11:17Z")
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Xeno C. wrote: | Please this is a Ruby question, not, at least as the main focus, a rails | one, as you’ll see if you read all the way through. | | Say, I’ve got a case in Rails where I want all my links to be prepended | with something like ~u1/rrsw/thingies so I can see | [http://host/~u1/rrsw/thingies](http://host/~u1/rrsw/thingies) and [http://host/~u2/rrsw/thingies](http://host/~u2/rrsw/thingies) instead | of [http://host:9001/thingies](http://host:9001/thingies) and [http://host:9002/thingies](http://host:9002/thingies) for a rails | tool that is used by some n projects. The rails part is apparently not | configurable, so I’m looking at redefining rails methods like link\_to to | stick the path in there. This should be reasonable, but I’m stuck on a | ruby problem: You are aware that the port of the URL is not under Rails’ nor Ruby’s control per se (it is the domain of the webserver)? URLs are composed in (roughly) six parts: the [protocol]://[host]:[port]/[user\_directory]/[directory/that/app/uses/or/rewrites]/[document\_requested.suffix] Of those, only the directory and explicit document are under control by any given web application. Further, you can only have one server listen on any given port (though, one server can listen on an unlimited number of ports). What you want, can be achieved by using Apache + mod\_rails. Uou can get the ~u1/~u2 part, by having different users on a, for example, UNIX based OS have their own web\_root (or web\_home, as it can be called, by convention), which would be reachable as host/~username/index.html (for example). Details of implementing such a setup can be found in various ways on, for example, [http://howtoforge.org](http://howtoforge.org). As far as overriding a Ruby method: You can usually achieve that by reopening the class, adding an alias for the old method, and defining your own implementation. Be careful, though, when you do. Where to do that so Rails picks up a change to link\_to, I do not know (I suspect it is in ActiveSupport, though). * * * Phillip G. Twitter: [twitter.com/cynicalryan](http://twitter.com/cynicalryan) Blog: [http://justarubyist.blogspot.com](http://justarubyist.blogspot.com) ~ - You know you’ve been hacking too long when… …your complexion has turned pale from being constantly irradiated by the monitor. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.8 (MingW32) Comment: Using GnuPG with Mozilla - [http://enigmail.mozdev.org](http://enigmail.mozdev.org) iEYEARECAAYFAkg3sU8ACgkQbtAgaoJTgL/zGgCcD/x24SNTx8OFslWJ5fX5A5gq x8UAniPPYbQl1pPj/ytTyFeoxS5Hp7N7 =Z9nu -----END PGP SIGNATURE----- ---
**Author:** ![Xeno\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/x/958977/32.png) [@Xeno\_C](https://www.ruby-forum.com/u/Xeno_C)\ **Post date:** [May 25, 2008, 1:56am UTC](https://www.ruby-forum.com/t/railsy-question-about-redefining-ruby-methods/138533/3 "2008-05-25T01:56:00Z")
Phillip G. wrote: > | of [http://host:9001/thingies](http://host:9001/thingies) and [http://host:9002/thingies](http://host:9002/thingies) for a rails > | tool that is used by some n projects. The rails part is apparently not > | configurable, so I’m looking at redefining rails methods like link\_to to > | stick the path in there. This should be reasonable, but I’m stuck on a > | ruby problem: No no no no no no! I have all the other stuff working. I’ve got UserDir and ProxyPass directives that get all the stuff set up initially from my [http://host](http://host):n to my [http://host/~u1/rrsw](http://host/~u1/rrsw) like I want. All I need now is to get all the URLs that are presently rendered in the markup as /something to be ~u1/rrsw/something. That is all I need. I have the rest working. So, thank you for your feedback. It is interesting for other reasons, but what I was asking about was the very thing you said you were unable to answer; nothing more. Sincerely, Xeno xc ---
**Author:** ![Xeno\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/x/958977/32.png) [@Xeno\_C](https://www.ruby-forum.com/u/Xeno_C)\ **Post date:** [May 25, 2008, 2:28am UTC](https://www.ruby-forum.com/t/railsy-question-about-redefining-ruby-methods/138533/4 "2008-05-25T02:28:09Z")
Hi – On Sat, 24 May 2008, Xeno C. wrote: > Please this is a Ruby question, not, at least as the main focus, a rails one, > as you’ll see if you read all the way through. Well, if my answer is correct, it’s a very Rails-specific question 🙂 > new redefinition in the module ApplicationHelpers, but I believe that may > short circuit the access, as I’m not seeing the example I put in which always > puts out a traceable constant, resulting in the expected changes in my test > web pages. So, and here is the question: > > Can anyone suggest how I should specify an appropriately available method for > the correct module inside another module so that it overrides the original in > the fashion I desire? I presume this is a simple problem, as it’s what > people do all the time in OO right? I’m still a little green on these > patterns yet I think. Have a look at relative\_url\_root, which I believe (though I haven’t used it in a while) does what you want. David ---
**Author:** ![Xeno\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/x/958977/32.png) [@Xeno\_C](https://www.ruby-forum.com/u/Xeno_C)\ **Post date:** [May 25, 2008, 2:13am UTC](https://www.ruby-forum.com/t/railsy-question-about-redefining-ruby-methods/138533/5 "2008-05-25T02:13:32Z")
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Xeno C. wrote: | No no no no no no! I have all the other stuff working. I’ve got | UserDir and ProxyPass directives that get all the stuff set up initially | from my [http://host](http://host):n to my [http://host/~u1/rrsw](http://host/~u1/rrsw) like I want. All I | need now is to get all the URLs that are presently rendered in the | markup as /something to be ~u1/rrsw/something. That is all I need. I | have the rest working. Why? Is the application not working? The webserver is smart enough to construct the link properly, so that links should Just Work™. And you don’t really want absolute links, either, as this will break once you move the application to another server. Otherwise, look at Rails’ routes.rb. * * * Phillip G. Twitter: [twitter.com/cynicalryan](http://twitter.com/cynicalryan) Blog: [http://justarubyist.blogspot.com](http://justarubyist.blogspot.com) Youth – not a time of life but a state of mind… a predominance of courage over timidity, of the appetite for adventure over the love of ease. ~ – Robert Francis Kennedy (1925-1968) -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.8 (MingW32) Comment: Using GnuPG with Mozilla - [http://enigmail.mozdev.org](http://enigmail.mozdev.org) iEYEARECAAYFAkg4rxoACgkQbtAgaoJTgL/YBACgpy5rJGR6uwqjmVNp2254HsrH 2SQAoKccu01YWo+xnag0qY2GTeKqYKCm =oIi1 -----END PGP SIGNATURE----- ---
**Author:** ![Xeno\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/x/958977/32.png) [@Xeno\_C](https://www.ruby-forum.com/u/Xeno_C)\ **Post date:** [May 25, 2008, 2:37am UTC](https://www.ruby-forum.com/t/railsy-question-about-redefining-ruby-methods/138533/6 "2008-05-25T02:37:31Z")
Phillip G. wrote: > | have the rest working. > > Why? Is the application not working? The webserver is smart enough to > construct the link properly, so that links should Just Work™. > > And you don’t really want absolute links, either, as this will break > once you move the application to another server. They aren’t absolute at all. What I get rendered by rails link\_to, for instance, is things like [Something](https://www.ruby-forum.com/something). What I need is still a relative link, which is Something for u1, and Something for u2. I originally expected there would be a simple rendering configuration for this in rails, and spent much of yesterday and part of Thursday asking on the #rubyonrails IRC. Not only did those folks know of no such configuration, but they didn’t seem to even understand the OO need for encapsulation, nor the logical reason, nor the traditional Unix Webserver usage of ~user, nowadays configured with the UserDir Apache directive. Anyway, those are mostly Rails oriented issues and problems, which are interesting, but not completely appropriate here. What is appropriate to address here is the whole idea of redefinition of a Ruby method like link\_to which is embedded in some arbitrary community/tree of modules and/or classes. I’ve never done much of that, and I know it’s part of the real power that experienced OO users acquire in such environments. Now ideally it would be nice if some Rails supergeek came out of the woodwork and said there in fact was a configuration to change the rendering, but it looks like there’s not. You wouldn’t want to change the URLs that Rails renders with an external rewrite in Apache if you can help it because that breaks encapsulation, which is a standard and a good ethic in OO programming any reasonable engineer would recognize, and given the ability to simply redefine link\_to, url\_for, or whatever other methods I use can achieve what I want, and not only that perhaps help lead to a future Rails configurability on such things in a reasonably elegant matter, presuming that it in fact doesn’t yet exist, seems to me to make that the proper direction for me at this point. Thanks for asking. ---
**Author:** ![Xeno\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/x/958977/32.png) [@Xeno\_C](https://www.ruby-forum.com/u/Xeno_C)\ **Post date:** [May 25, 2008, 10:49pm UTC](https://www.ruby-forum.com/t/railsy-question-about-redefining-ruby-methods/138533/7 "2008-05-25T22:49:51Z")
David A. Black wrote: > Hi – > > On Sat, 24 May 2008, Xeno C. wrote: I’m cutting this short and just saying that David Black’s suggestion works regarding: > Have a look at relative\_url\_root, which I believe (though I haven’t > used it in a while) does what you want. Since this is a ruby group, and the suggestion is rails, I am going to top off my discussion directly to my two correspondencts. Thank you. ---
**Author:** ![Xeno\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/x/958977/32.png) [@Xeno\_C](https://www.ruby-forum.com/u/Xeno_C)\ **Post date:** [May 25, 2008, 2:39am UTC](https://www.ruby-forum.com/t/railsy-question-about-redefining-ruby-methods/138533/8 "2008-05-25T02:39:16Z")
David A. Black wrote: > Hi – > > On Sat, 24 May 2008, Xeno C. wrote: > > > Please this is a Ruby question, not, at least as the main focus, a > > rails one, as you’ll see if you read all the way through. > > Well, if my answer is correct, it’s a very Rails-specific question 🙂 Thank you David. I’ll look at this right now, and try to have an answer by tomorrow afternoon, as my evening is about to draw me away.’ Sincerely, Xeno ---
**Author:** ![Xeno\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/x/958977/32.png) [@Xeno\_C](https://www.ruby-forum.com/u/Xeno_C)\ **Post date:** [May 27, 2008, 1:40pm UTC](https://www.ruby-forum.com/t/railsy-question-about-redefining-ruby-methods/138533/9 "2008-05-27T13:40:34Z")
Have you looked at the rails routes table?