From: Warren Brown <WBrown@...>
Date: 2004-09-23T08:01:00+09:00
Subject: Re: Newbie: Case statement

Graham,

> As a newbie I'm confused about the Case construct. All
> the documentation I've found states "case operates by
> comparing the target with EACH of the expressions after
> the When keyword"

    The documentation should continue with "performing (expression ===
target), until the comparison returns true"

> So my underlying question is:- what's the fastest Ruby
> for checking which of the 8 possible adjacent cells on
> a board (2D array) are still "on the board"

    This is a very ambiguous question, but I think the answer to "what's
the fastest" is going to be testing each of the eight cells
individually.  For example:

cells_left = [
  cell[x - 1][y - 1],
  cell[x    ][y - 1],
  cell[x + 1][y - 1],
  cell[x - 1][y    ],
  cell[x + 1][y    ],
  cell[x - 1][y +  ],
  cell[x    ][y + 1],
  cell[x + 1][y + 1],
].compact

    I hope this helps.

    - Warren Brown