In ruby even the base types (also predefined classes) can be hacked. In the following example, 5 is an immediate, a literal, an object, and an instance of Fixnum.
alias other_s to_s
a = self + 5
a = 5
puts a.class ## prints Fixnum
puts a ## prints 10 (adds 5 once)
puts 0 ## prints 5 (adds 5 once)
puts 5 ## prints 10 (adds 5 once)
puts 10 + 0 ## prints 15 (adds 5 once)
b = 5+5
puts b ## puts 15 (adds 5 once)
- ^ Which means the 4 VALUE bytes are not a reference but the value itself. All 5 have the same object id (which could also be achieved in other ways).
- ^ Might not always work as you would like, the base types don't have a constructor (
def initialize), and can't have simpleton methods. There are some other minor exceptions.