# Calling class methods from C **URL:** \ **Category:** ruby-talk\ **Created:** [22 January 2009 19:11 UTC](https://rubytalk.org/t/calling-class-methods-from-c/51321 "2009-01-22T19:11:09Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Robert\_Rouse](https://avatars.discourse-cdn.com/v4/letter/r/91b2a8/32.png) [@Robert\_Rouse](https://rubytalk.org/u/Robert_Rouse)\ **Post date:** [22 January 2009 19:11 UTC](https://rubytalk.org/t/calling-class-methods-from-c/51321/1 "2009-01-22T19:11:09Z")
Hello, I'm trying to call a class method from C. I've tried all combinations of rb\_intern I could think of to make it work, but I've gotten nothing. Example class class CallTest def go (do something here) end end rb\_funcall(?, rb\_intern("go"), 0); What goes in the ? space? I know if I use Qnil there, it will call global functions, but I'd prefer class methods. Am I heading in the wrong direction? Also, I'd prefer not to have to know the class name ahead of time if possible, but if I have to require that I know what it is, I can try passing it by name to my application. I'm using SWIG to generate the binding. > **···** > > -- > Posted via [http://www.ruby-forum.com/](http://www.ruby-forum.com/). ---
**Author:** ![Jason\_R](https://avatars.discourse-cdn.com/v4/letter/j/94ad74/32.png) [@Jason\_R](https://rubytalk.org/u/Jason_R)\ **Post date:** [22 January 2009 19:23 UTC](https://rubytalk.org/t/calling-class-methods-from-c/51321/2 "2009-01-22T19:23:45Z")
From the top of my head: rb\_funcall(rb\_const\_get("CallTest"), rb\_intern("go"), 0); And if you're calling "global" methods, it's better to call it on Kernel, where the methods are defined anyway: rb\_funcall(rb\_mKernel, rb\_intern("method\_name"), args); Hope that helps. Jason > **···** > > On Thu, Jan 22, 2009 at 2:11 PM, Robert Rouse \ wrote: > > > Hello, > > > > I'm trying to call a class method from C. I've tried all combinations of > > rb\_intern I could think of to make it work, but I've gotten nothing. > > > > Example class > > > > class CallTest > > def go > > (do something here) > > end > > > > end > > > > rb\_funcall(?, rb\_intern("go"), 0); > > > > What goes in the ? space? I know if I use Qnil there, it will call > > global functions, but I'd prefer class methods. > > > > Am I heading in the wrong direction? > > > > Also, I'd prefer not to have to know the class name ahead of time if > > possible, but if I have to require that I know what it is, I can try > > passing it by name to my application. > > > > I'm using SWIG to generate the binding. > > -- > > Posted via [http://www.ruby-forum.com/\](http://www.ruby-forum.com/%5C). ---
**Author:** ![Jason\_R](https://avatars.discourse-cdn.com/v4/letter/j/94ad74/32.png) [@Jason\_R](https://rubytalk.org/u/Jason_R)\ **Post date:** [22 January 2009 19:28 UTC](https://rubytalk.org/t/calling-class-methods-from-c/51321/3 "2009-01-22T19:28:02Z")
Bah, saw a small issue right when I hit "Send". My call line works for a class defined as such: class CallTest    def self.go       (do something here)    end end If you need to call an instance method on an instance of the class CallTest, you need to of course get a hold of that instance, or make a new one: VALUE obj = rb\_funcall(rb\_const\_get("CallTest"), rb\_intern("new"), 0); rb\_funcall(obj, rb\_intern("go"), 0); Jason > **···** > > On Thu, Jan 22, 2009 at 2:19 PM, Jason Roelofs \ wrote: > > > From the top of my head: > > > > rb\_funcall(rb\_const\_get("CallTest"), rb\_intern("go"), 0); > > > > And if you're calling "global" methods, it's better to call it on > > Kernel, where the methods are defined anyway: > > > > rb\_funcall(rb\_mKernel, rb\_intern("method\_name"), args); > > > > Hope that helps. > > > > Jason > > > > On Thu, Jan 22, 2009 at 2:11 PM, Robert Rouse \ wrote: > > > > > Hello, > > > > > > I'm trying to call a class method from C. I've tried all combinations of > > > rb\_intern I could think of to make it work, but I've gotten nothing. > > > > > > Example class > > > > > > class CallTest > > > def go > > > (do something here) > > > end > > > > > > end > > > > > > rb\_funcall(?, rb\_intern("go"), 0); > > > > > > What goes in the ? space? I know if I use Qnil there, it will call > > > global functions, but I'd prefer class methods. > > > > > > Am I heading in the wrong direction? > > > > > > Also, I'd prefer not to have to know the class name ahead of time if > > > possible, but if I have to require that I know what it is, I can try > > > passing it by name to my application. > > > > > > I'm using SWIG to generate the binding. > > > -- > > > Posted via [http://www.ruby-forum.com/\](http://www.ruby-forum.com/%5C). ---
**Author:** ![Robert\_Rouse](https://avatars.discourse-cdn.com/v4/letter/r/91b2a8/32.png) [@Robert\_Rouse](https://rubytalk.org/u/Robert_Rouse)\ **Post date:** [22 January 2009 19:34 UTC](https://rubytalk.org/t/calling-class-methods-from-c/51321/4 "2009-01-22T19:34:21Z")
Jason Roelofs wrote: > Bah, saw a small issue right when I hit "Send". > > My call line works for a class defined as such: > > class CallTest >    def self.go >       (do something here) >    end > end > > If you need to call an instance method on an instance of the class > CallTest, you need to of course get a hold of that instance, or make a > new one: > > VALUE obj = rb\_funcall(rb\_const\_get("CallTest"), rb\_intern("new"), 0); > rb\_funcall(obj, rb\_intern("go"), 0); > > Jason I tried using rb\_const\_get but it doesn't appear to call the method. What should I use for those parameters (VALUE and ID)? > **···** > > -- > Posted via [http://www.ruby-forum.com/\](http://www.ruby-forum.com/%5C).