From: Florian Gross <flgr@...>
Date: 2004-09-23T21:04:33+09:00
Subject: Re: Newbie: Case statement

Graham Foster wrote:

> 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"
> This does NOT appear to happen, as only the first match is ever 
> actioned, so overlapping WHEN cases are skipped.
> I assume this is expected behaviour? (I'm ex-C - and was looking for 
> fall-through behaviour)

Yup, you can use this as a case that checks all options:

def greedy_case(obj, cases)
   cases.find_all do |condition, action|
     condition === obj
   end.inject(Hash.new) do |hash, (condition, action)|
     hash[condition] = action.call; hash
   end
end

def test(x)
   greedy_case(x,
     1 .. 2 => lambda { puts "In A" },
     1 .. 3 => lambda { puts "In B" },
     2 .. 4 => lambda { puts "In C" })
end

test(2)

Regards,
Florian Gross