weakref.mri.rb

ruby-1.8.7-p174 > WeakRef
NameError: uninitialized constant WeakRef
        from (irb):1
ruby-1.8.7-p174 > require 'weakref'
 => true 
ruby-1.8.7-p174 > WeakRef
 => WeakRef 
ruby-1.8.7-p174 > 

weakref.rbx.rb

rbx-1.0.1-20100603 > require 'weakref'
LoadError: no such file to load -- weakref
   from Rubinius::CodeLoader#load_error at kernel/common/codeloader.rb:343
   from Rubinius::CodeLoader#resolve_require_path at kernel/common/codeloader.rb:330
   from Rubinius::CodeLoader#require at kernel/common/codeloader.rb:34
   from Rubinius::CodeLoader.require at kernel/common/codeloader.rb:140
   from Kernel(Object)#gem_original_require (require) at kernel/common/kernel.rb:693
   from Kernel(Object)#require at /Users/cowboyd/.rvm/rubies/rbx-1.0.1-20100603/lib/rubygems/custom_require.rb:31
   from Object#irb_binding {} at (irb):1
rbx-1.0.1-20100603 > WeakRef
 => WeakRef 
rbx-1.0.1-20100603 > w = WeakRef.new(Object.new)
 => #<WeakRef:0x21c object=#<Object:0x21e>> 
rbx-1.0.1-20100603 > w.weakref_alive?