gistfile1.txt

class Foo
  def self.bar
  end

  def bar
  end
end

set_trace_func proc { |event, file, line, id, binding, classname|
  if event == "call"
    p eval("self", binding) == classname
  end
}

foo = Foo.new

Foo.bar
foo.bar

# => true
# => false