- design principle of the day:
  - use polymorphism rather than explicit tests
    - replace "switch" statements with polymorphism
    - don't switch based on data
    - instead, let objects decide what functionality they
      should have for their own data
  - case study
    - research code that I'm currently writing
    - currently:
      - 2036 lines of code
      - 30 different classes/interfaces
      - 4 packages
      - _0_ case statements
      - 40 occurrences of the string "if"
        - 6 in comment strings
        - 4 in .equals() methods ==> down casts
          if (!(o instanceof ClassFoo)) { return false; }
        - 24 of remaining in single method
          - testing line segment intersection
          - lots of nasty sub-cases (parallel, degenerate segments,
            etc.)
          - I looked hard, but haven't found a better way to handle it
            (yet!)
        - otherwise, only _6_ if statements (and 2 of those go to
          support the big, nasty method!)
- advice for RL alg params
  0.3 <= \alpha <= 0.7
  0.9 <= \gamma < 1