Override default Object#to_s preserving class and encoded id like #<Nokogiri::XML::Element:0x11ab674 @var="123" ...

default_object_to_s.rb

# This reimplementation produces the following sample result
# => #<Object:0x000000018436d0 @var=3>
def to_s
  "#<%s:%#0.14x @var=%s>" % [self.class, self.__id__.abs*2, var]
end

# It is also possible to minify it by tweaking precision an getting rid
# of all those zeros like so:
# => #<Object:0x18436d0 @var=3>
def to_s
  "#<%s:%#x @var=%s>" % [self.class, self.__id__.abs*2, var]
end