Is it possible to define a Ruby singleton method using a block?
Object#define_singleton_method was added to ruby-1.9.2 by the way:
def define_say(obj, msg) obj.define_singleton_method(:say) do puts msg endend
Here's an answer which does what you're looking for
def define_say(obj, msg) # Get a handle to the singleton class of obj metaclass = class << obj; self; end # add the method using define_method instead of def x.say so we can use a closure metaclass.send :define_method, :say do puts msg endendUsage (paste from IRB)
>> s = "my string"=> "my string">> define_say(s, "I am S")=> #<Proc:0xb6ed55b0@(irb):11>>> s.sayI am S=> nilFor more info (and a little library which makes it less messy) read this:
http://viewsourcecode.org/why/hacking/seeingMetaclassesClearly.html
As an aside, If you're a ruby programmer, and you HAVEN'T read that, go do it now~!