From: yermej <yermej@...>
Date: 2007-12-02T13:09:59+09:00
Subject: Re: Scrabble Stems Ruby Quiz question.

On Dec 1, 8:48 pm, Mark Woodward <markonli...@internode.on.net> wrote:
> Hi all,
>
> could someone explain the line:
>     (STEMS[stem] ||= {})[letter] = 1
> in the code below?

It's equivalent to:

STEMS[stem] = STEMS[stem] || {}
STEMS[stem][letter] = 1

Where that first line means: if STEMS[stem] isn't defined, assign a
new Hash to it.

It could also be done like this:

STEMS = Hash.new {|h, k| h[k] = {}} # near the top of your example
code

STEMS[stem][letter] = 1 # and this in place of the line you asked
about

Hash.new allows you to use a block to define the behavior of the hash
if the element isn't found. With no block (as in the example code you
posted), nil is returned.