# Dynamically changing class methods **URL:** \ **Category:** ruby-talk\ **Created:** [11 August 2005 15:46 UTC](https://rubytalk.org/t/dynamically-changing-class-methods/20095 "2005-08-11T15:46:11Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![henrikbrink](https://avatars.discourse-cdn.com/v4/letter/h/a9adbd/32.png) [@henrikbrink](https://rubytalk.org/u/henrikbrink)\ **Post date:** [11 August 2005 15:46 UTC](https://rubytalk.org/t/dynamically-changing-class-methods/20095/1 "2005-08-11T15:46:11Z")
Hello! Im making an application that loads and uses the methods of a class dynamically. The class can then be altered while the application is running, and the application loads the file containing the class every time it is needed. The strange thing is: It works fine when i add a method to the class. The new method shows up. But if i remove a method, it acts as if it was still there. How can that be? Here's the code used to get the methods:     load "#{file}.rb"     myclass = Object.const\_get "MyClass"     myclass\_inst = myclass.new     methods = myclass\_inst.methods If I am not clear enough, please ask. Regards, Henrik ---
**Author:** ![Bill\_Atkins](https://avatars.discourse-cdn.com/v4/letter/b/c4cdca/32.png) [@Bill\_Atkins](https://rubytalk.org/u/Bill_Atkins)\ **Post date:** [11 August 2005 15:56 UTC](https://rubytalk.org/t/dynamically-changing-class-methods/20095/2 "2005-08-11T15:56:15Z")
How are you removing the method? > **路路路** > > On 8/11/05, henrikbrink \ wrote: > > > Hello! > > > > Im making an application that loads and uses the methods of a class > > dynamically. The class can then be altered while the application is > > running, and the application loads the file containing the class every > > time it is needed. > > > > The strange thing is: It works fine when i add a method to the class. > > The new method shows up. But if i remove a method, it acts as if it was > > still there. How can that be? > > > > Here's the code used to get the methods: > > > >     load "#{file}.rb" > >     myclass = Object.const\_get "MyClass" > >     myclass\_inst = myclass.new > >     methods = myclass\_inst.methods > > > > If I am not clear enough, please ask. > > > > Regards, Henrik > > -- > Bill Atkins ---
**Author:** ![David\_A\_Black3](https://avatars.discourse-cdn.com/v4/letter/d/6a8cbe/32.png) [@David\_A\_Black3](https://rubytalk.org/u/David_A_Black3)\ **Post date:** [11 August 2005 15:57 UTC](https://rubytalk.org/t/dynamically-changing-class-methods/20095/3 "2005-08-11T15:57:12Z")
Hi -- > Hello! > > Im making an application that loads and uses the methods of a class > dynamically. The class can then be altered while the application is > running, and the application loads the file containing the class every > time it is needed. > > The strange thing is: It works fine when i add a method to the class. > The new method shows up. But if i remove a method, it acts as if it was > still there. How can that be? > > Here's the code used to get the methods: > >    load "#{file}.rb" >    myclass = Object.const\_get "MyClass" >    myclass\_inst = myclass.new >    methods = myclass\_inst.methods If you do this:    class MyClass      def some\_method        # ...      end    end and then, later, do this:    class MyClass    end (i.e., don't define some\_method), some\_method is still there. The effects of opening a class multiple times are cumulative. This is the case whether it's all in one file or in multiple files, or even in the same file loaded multiple times. If you want to remove a method, you have to use remove\_method or under\_method (which are slightly different from each other; see ri or other docs). > If I am not clear enough, please ask. Same here 馃檪 David > **路路路** > > On Fri, 12 Aug 2005, henrikbrink wrote: > > -- > David A. Black > dblack@wobblini.net ---
**Author:** ![Ara.T.Howard6](https://avatars.discourse-cdn.com/v4/letter/a/958977/32.png) [@Ara.T.Howard6](https://rubytalk.org/u/Ara.T.Howard6)\ **Post date:** [11 August 2005 16:00 UTC](https://rubytalk.org/t/dynamically-changing-class-methods/20095/4 "2005-08-11T16:00:56Z")
because:    harp:~ \> irb    irb(main):001:0\> class Foo;def foo;end;end    irb(main):002:0\> p Foo::instance\_methods - Object::instance\_methods    ["foo"]    irb(main):003:0\> class Foo;def bar;end;end    irb(main):004:0\> p Foo::instance\_methods - Object::instance\_methods    ["bar", "foo"] opening up a class, even in a file that's loaded, can only add or modify methods using 'def'. there is a mechanism to delete methods but it must be explicit. for dynamically loading classes try this:      jib:~ \> cat b.rb        require 'dynaload'        loaded = Dynaload::dynaload 'a.rb'        loaded.classes.each do |klass, attributes|          p [klass, attributes]          p klass.instance\_methods - Object.instance\_methods        end      jib:~ \> cat a.rb        require 'dynaload'        class Foo          def foo          end        end        Dynaload::export Foo, 'some attribute' =\> 42      jib:~ \> ruby b.rb        [#\::Foo, {"some attribute"=\>42}]        ["foo"]      jib:~ \> cat a.rb        require 'dynaload'        class Foo          def bar          end        end        Dynaload::export Foo, 'some attribute' =\> 42      jib:~ \> ruby b.rb        [#\::Foo, {"some attribute"=\>42}]        ["bar"] [http://raa.ruby-lang.org/project/dynaload/](http://raa.ruby-lang.org/project/dynaload/) > **[Index of /lib/ruby/dynaload](https://www.codeforpeople.com/lib/ruby/dynaload/)** hth. -a > **路路路** > > On Fri, 12 Aug 2005, henrikbrink wrote: > > > Hello! > > > > Im making an application that loads and uses the methods of a class > > dynamically. The class can then be altered while the application is > > running, and the application loads the file containing the class every > > time it is needed. > > > > The strange thing is: It works fine when i add a method to the class. > > The new method shows up. But if i remove a method, it acts as if it was > > still there. How can that be? > > > > Here's the code used to get the methods: > > > >    load "#{file}.rb" > >    myclass = Object.const\_get "MyClass" > >    myclass\_inst = myclass.new > >    methods = myclass\_inst.methods > > > > If I am not clear enough, please ask. > > > > Regards, Henrik > > # -- > > > email :: ara [dot] t [dot] howard [at] noaa [dot] gov > > phone :: 303.497.6469 > > Your life dwells amoung the causes of death Like a lamp standing in a strong breeze. --Nagarjuna > > =============================================================================== ---
**Author:** ![Joel\_VanderWerf1](https://avatars.discourse-cdn.com/v4/letter/j/94ad74/32.png) [@Joel\_VanderWerf1](https://rubytalk.org/u/Joel_VanderWerf1)\ **Post date:** [11 August 2005 20:02 UTC](https://rubytalk.org/t/dynamically-changing-class-methods/20095/5 "2005-08-11T20:02:29Z")
Aside from the suggestions so far, you might want to take a look at [http://raa.ruby-lang.org/project/script/](http://raa.ruby-lang.org/project/script/). Just another approach to encapsulating the definitions in a loaded script file... > **路路路** > > -- >       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407 ---
**Author:** ![henrikbrink](https://avatars.discourse-cdn.com/v4/letter/h/a9adbd/32.png) [@henrikbrink](https://rubytalk.org/u/henrikbrink)\ **Post date:** [11 August 2005 19:56 UTC](https://rubytalk.org/t/dynamically-changing-class-methods/20095/6 "2005-08-11T19:56:10Z")
I can see now why my code didn't work, and i must say... doh! But I'm glad I asked anyway as Dynaload does the job! Thank you everyone!