README

[lifo@null rock (master)]$ ruby extconf.rb && make
[lifo@null rock (master)]$ ruby run.rb

extconf.rb

require 'mkmf'
extension_name = 'rock'

dir_config(extension_name)
create_makefile(extension_name)

rock.c

#include "ruby.h"
#include "node.h"

static ID hook_method;

void method_call(rb_event_t event, NODE *node, VALUE self, ID id, VALUE klass) {
  char * called_method;
  called_method = rb_id2name(id);

  VALUE hook_exists = rb_obj_respond_to(self, hook_method, Qtrue);

  if(hook_exists == Qtrue && strcmp(called_method, "method_call_hook") != 0) {
    rb_funcall(self, hook_method, 0);
  }
}

void Init_rock() {
  hook_method = rb_intern("method_call_hook");

  rb_add_event_hook(&method_call, RUBY_EVENT_CALL);
}

run.rb

require 'rock'

class Hello
  def world
  end

  def method_call_hook
    puts "My bloody hook"
  end
end

h = Hello.new
h.world