singleton.rb

class Foo
  def hello
    :regular_instance_method
  end
end

def singleton_class_for(obj)
  class << obj; self; end
end

# public_instance_methods(false) is supposed to give a list of methods defined
# on the Class or Module, *not including ancestors*

# I expect these values:
# On 1.9.2, 1.9.3: [:hello]
# On 1.8.7: ["hello"]
p Foo.public_instance_methods(false)

# On 1.9.2, 1.9.3: []
# On 1.8.7: ["hello"] <-- WHY? I DID NOT EXPECT THIS
p singleton_class_for(Foo.new).public_instance_methods(false)

Can you use this?

(singleton_class_for(Foo.new).public_instance_methods(false) - Foo.public_instance_methods(false))

That returns [] on both 1.8.7 and 1.9.

@myronmarston, good point, but it's possible in my use case that it'll be defined in both places. I want to know definitively if it's defined on the singleton class, regardless of whether it's on any superclass.