String#sum( n = 16 ) computes an n-bit checksum for a string. This amounts to addition of the character codes for a string. Proof: ?R + ?H <redpre#0> “RH”.sum. The clash between checksums is large.

A slightly better checksum is Object#hash, a method attached to every Ruby object. Since Object#hash uses a multiplier and bit shifter, its clash is diminished. While it is less predictable than String#sum, the hash from Object#hash can still be easily reversed, so don’t expect security from this hash.

As it stands, String#sum works for character math and Object#hash works for simplifying storage of Hash keys.

Note: Method Check is a column which investigates usage of a single method available in Ruby or a Ruby library. Ri conventions are used. The octothorpe symbol # is used to identify instance methods (such as Object#object_id), while the double-colon :: is used for class methods (such as Object::new.)