From: Devin Mullins <twifkak@...>
Date: 2007-02-15T15:03:59+09:00
Subject: Re: Drying a ternary condition

Marcello Barnaba wrote:
>>dirs = %w{up down}
>>klass.send(dirs.find(dirs.first) {|dir| dir == ARGV[0] })
>
> clever use of .first (setting the default) and .find.
well, it turns out, not so clever. i got the api wrong - find expects 
the arg to be a Proc. (also there's a typo in the above.) meh:
   klass.send(%w{up down}.grep(ARGV[0])[0] || 'up')
readability? what's that?

> but I think that readability hit a regression.. and first we stood in front of 
> 3 ups, now we stand in front of 4 dirs! :)

Well, it's likely the wrong place for the code, but while we're hunting 
for [what is probably more textual duplication than duplication of 
knowledge]:

module Enumerable
   def match_or_first(obj)
     self[index(obj) || 0]
   end
end

klass.send(%w{up down}.match_or_first(ARGV[0])

Don't like the duplicated 'obj'?

Class.new(Array) {
   def index(*a)
     self[super || 0]
   end

   klass.send(new(%w{up down}).index(ARGV[0]))
}

Now I just to find a way to factor out the duplicated 'new' and '0'...

Devin