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This is an alternative to _why's mix_eval C extension. It provides identical functionality to mix_eval as well as the following extra functionality:

  • Ability to mix in Objects/Classes (using Object2module)
  • Thread-safety

Dup_eval is based on coderrr's idea for dupping the binding of a block (

NOTE: Dup_eval is still in proof of concept stage, use at own risk!

Example use:

#create our object
o =

#give it a method
class << o
    def hello; print "Hello! "; end

#create a method in the current binding
def goodbye; puts "Goodbye!"; end

o.dup_eval { hello; goodbye }    #=> "Hello! Goodbye!" 

From above, both the methods of the object itself and the binding of the block are available to the block.

#we can also choose which objects we want to eval the block with respect to (we can have more than one)
o1 =
class << o1; ...define methods here... end

o2 =
class << o2; ...define methods here... end

o3 =
class << o3; ...define methods here... end

#create a method in the current binding
def goodbye; puts "Goodbye!"; end

o1.dup_eval_with(o1, o2, o3) { o1_method; o2_method; o3_method; goodbye }

As shown above we can have the block access methods in many objects (as many as we want). The objects may also be either Objects, Classes, or Modules.