# Including a class **URL:** \ **Category:** Ruby\ **Created:** [August 29, 2006, 10:04am UTC](https://www.ruby-forum.com/t/including-a-class/66786 "2006-08-29T10:04:30Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Ola\_B](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/858c86/32.png) [@Ola\_B](https://www.ruby-forum.com/u/Ola_B)\ **Post date:** [August 29, 2006, 10:04am UTC](https://www.ruby-forum.com/t/including-a-class/66786/1 "2006-08-29T10:04:30Z")
Hi, As an extension on my earlier question of partial includes; I just noticed that you can’t include a Class, even though it is a Module. Anyone have a way of doing this? What I would like to do, is to be able to dynamically mix in some good methods from preexisting classes, depending on arguments to the constructor. Since I need to do it dynamically, and also need it differently for different instances of the class, I can’t make it inherit the other class. What I would like is something like this; say I have class Foo and Bar, with many methods in them. class Baz \< AnotherAbstractBaseClass def initialize(config={}) self.singleton\_class.module\_eval do if config[:foo] partial\_include Foo, :method1, :method7 elsif config[:bar] partial\_include Bar, :method1, :method7 end end end end Baz.new(:bar =\> true).method1 But I can’t have an instance of Bar or Foo so delegating is impossible. I need the methods to be in the the same instance. Any help? =) – Ola B. ([http://ola-bini.blogspot.com](http://ola-bini.blogspot.com)) JvYAML, RbYAML, JRuby and Jatha contributor System Developer, Karolinska Institutet ([http://www.ki.se](http://www.ki.se)) OLogix Consulting ([http://www.ologix.com](http://www.ologix.com)) “Yields falsehood when quined” yields falsehood when quined. ---
**Author:** ![Ola\_B](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/858c86/32.png) [@Ola\_B](https://www.ruby-forum.com/u/Ola_B)\ **Post date:** [August 29, 2006, 10:40am UTC](https://www.ruby-forum.com/t/including-a-class/66786/2 "2006-08-29T10:40:34Z")
On Tue, Aug 29, 2006 at 05:02:10PM +0900, Ola B. wrote: > As an extension on my earlier question of partial includes; I just > noticed that you can’t include a Class, even though it is a Module. > > Anyone have a way of doing this? > > What I would like to do, is to be able to dynamically mix in some good > methods from preexisting classes, depending on arguments to the > constructor. Since I need to do it dynamically, and also need it > differently for different instances of the class, I can’t make it > inherit the other class. > […] > But I can’t have an instance of Bar or Foo so delegating is impossible. > ======================== > I need the methods to be in the the same instance. Doesn’t this provide a very strong indication that you want to put the reusable methods in modules? 🙂 RUBY\_VERSION # =\> “1.8.5” RUBY\_RELEASE\_DATE # =\> “2006-08-25” module A; def foo; “A#foo” end end module B; def foo; “B#foo” end end class X; include A end class Y; include B end class Z def initialize(config = {}) if config[:A] extend A elsif config[:B] extend B end end end Z.new(:A =\> true).foo # =\> “A#foo” Z.new(:B =\> true).foo # =\> “B#foo” [See [211308] for a Module#append\_from implementation that doesn’t clobber inherited methods.] ---
**Author:** ![Ola\_B](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/858c86/32.png) [@Ola\_B](https://www.ruby-forum.com/u/Ola_B)\ **Post date:** [August 29, 2006, 10:56am UTC](https://www.ruby-forum.com/t/including-a-class/66786/3 "2006-08-29T10:56:35Z")
Mauricio F. wrote: > > inherit the other class. > > […] > > > But I can’t have an instance of Bar or Foo so delegating is impossible. > > ======================== > > I need the methods to be in the the same instance. > > Doesn’t this provide a very strong indication that you want to put the > reusable methods in modules? 🙂 See, that’s my problem. I have no control over them. Let me explain. I’m working on ActiveRecord-JDBC, and sorry to say, some features of JDBC aren’t really database independent (for example, DDL). So, my current track is to include parts of the original implementation to avoid this problem. Right now I have copied the source verbatim, but that is no solution. I want AR-JDBC to recognize that it’s being used with an Oracle JDBC driver, and then include some parts of OracleAdapter, (but only parts…) – Ola B. ([http://ola-bini.blogspot.com](http://ola-bini.blogspot.com)) JvYAML, RbYAML, JRuby and Jatha contributor System Developer, Karolinska Institutet ([http://www.ki.se](http://www.ki.se)) OLogix Consulting ([http://www.ologix.com](http://www.ologix.com)) “Yields falsehood when quined” yields falsehood when quined. ---
**Author:** ![Ola\_B](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/858c86/32.png) [@Ola\_B](https://www.ruby-forum.com/u/Ola_B)\ **Post date:** [August 29, 2006, 4:43pm UTC](https://www.ruby-forum.com/t/including-a-class/66786/4 "2006-08-29T16:43:30Z")
Ola B. wrote: > Mauricio F. wrote: > > > > inherit the other class. > > > […] > > > > > But I can’t have an instance of Bar or Foo so delegating is impossible. > > > ======================== > > > I need the methods to be in the the same instance. > > > > Doesn’t this provide a very strong indication that you want to put the > > reusable methods in modules? 🙂 > > See, that’s my problem. I have no control over them. Let me explain. I’m > working on ActiveRecord-JDBC, and sorry to say, some features of JDBC > aren’t really database independent (for example, DDL). So, my current > track is to include parts of the original implementation to avoid this > problem. Right now I have copied the source verbatim, but that is no > solution. I want AR-JDBC to recognize that it’s being used with an > Oracle JDBC driver, and then include some parts of OracleAdapter, (but > only parts…) Will simple composition and delegation work? > – > Ola B. ([http://ola-bini.blogspot.com](http://ola-bini.blogspot.com))