# Is engine for me or how do i solve this with engine? **URL:** \ **Category:** Engines\ **Created:** [April 29, 2007, 9:06am UTC](https://www.ruby-forum.com/t/is-engine-for-me-or-how-do-i-solve-this-with-engine/93208 "2007-04-29T09:06:10Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![Linn\_Hutchinson](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/ac8455/32.png) [@Linn\_Hutchinson](https://www.ruby-forum.com/u/Linn_Hutchinson)\ **Post date:** [April 29, 2007, 9:06am UTC](https://www.ruby-forum.com/t/is-engine-for-me-or-how-do-i-solve-this-with-engine/93208/1 "2007-04-29T09:06:10Z")
Hi: I have many small rails app under i.e app1, app2, app3 these are all independent applications except they all uses “same database”. Now I was thinking I would make a “common app” which can become an engine. Which means I will need to drop the “common app” to all of my rails app under “vendor” correct? no? Just to clarify my understanding … app1 -vendor -common\_functionality\_app\_as\_engine app2 -vendor -common\_functionality\_app\_as\_engine How can I avoid the above situation i.e. have a one “common app” is it possible to have the common app the following way -app1 -app2 -common\_functionality\_app\_as\_engine and then in app1/config/enviornments.rb … I add some text to point that my app is located in /path/to/common\_app… Is that possible? could you please tell me how? is this a via able approach? what are the downside? Regards Linn ---
**Author:** ![Linn\_Hutchinson](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/ac8455/32.png) [@Linn\_Hutchinson](https://www.ruby-forum.com/u/Linn_Hutchinson)\ **Post date:** [May 27, 2007, 5:08am UTC](https://www.ruby-forum.com/t/is-engine-for-me-or-how-do-i-solve-this-with-engine/93208/2 "2007-05-27T05:08:36Z")
Hi Linn, Your description about using vendor is almost right. It would be vendor/plugins/common\_functionality\_app\_as\_engine Yes, using engines is certainly possible if you use version control like subvesion. You would set up a subversion external to your engine in vendor/plugins. I suppose if you are in a unix environment you could use a an alias instead of an extern. I actually use the subversion external method to share code between my apps. It does mean you have to do svn update on each app that uses common\_functionality\_app\_as\_engine if you change common\_functionality\_app\_as\_engine. Another way would be to modify the load path in environment.rb (ex [http://www.benjaminbooth.com/tableorbooth/2006/11/rails\_and\_load\_.html](http://www.benjaminbooth.com/tableorbooth/2006/11/rails_and_load_.html)) and make all your apps include the common apps. The advantage of engines over this is engines makes it easier to modify your common functionality classes. With engines you can define a class with the same name if you local app/models (or controlers/views), and it is pretty smart about using yours or mixing your new methods in with the plugin’s files. Similar to the last method you could use externs in app/models|controllers|views. Again it might be tricky to extend the base classes. -Andrew Linn Hutchinson wrote: > Hi: > > I have many small rails app under i.e app1, app2, app3 these are all > independent applications except they all uses “same database”. Now I was > thinking I would make a “common app” which can become an engine. Which > means I will need to drop the “common app” to all of my rails app under > “vendor” correct? no? Just to clarify my understanding … > > app1 > -vendor > -common\_functionality\_app\_as\_engine > app2 > -vendor > -common\_functionality\_app\_as\_engine > > How can I avoid the above situation i.e. have a one “common app” is it > possible to have the common app the following way > > -app1 > -app2 > -common\_functionality\_app\_as\_engine > > and then in app1/config/enviornments.rb … I add some text to point > that my app is located in /path/to/common\_app… > > Is that possible? could you please tell me how? is this a via able > approach? what are the downside? > > Regards > Linn