http://stackoverflow.com/questions/10068018/memory-size-of-a-hash-or-other-object

http://stackoverflow.com/questions/16456513/size-of-class-in-bytes

[2] pry(main)> require 'objspace'
=> true
[3] pry(main)> p ObjectSpace.memsize_of("a" * 23)
0
=> 0
[4] pry(main)> p ObjectSpace.memsize_of("a" * 24)
24
=> 24

strings can be embedded in an RString structure if they are short, but stored in the heap if they are long (Never create Ruby strings longer than 23 characters).