From: Joel VanderWerf <vjoel@...>
Date: 2007-04-16T04:22:38+09:00
Subject: Re: Idiom wanted (now hiring!)


 > On Apr 13, 1:02 am, Jonathan <terho...@gmail.com> wrote:
 >> Is there a cool way to do this without calling the function twice?:
 >>
 >> a = func(b) unless func(b).nil? (AKA)
 >> a = func(b) if func(b)


greg wrote:
> assuming a is already defined
> 
> class Object;   def yield; yield(self) end end
> 
> func(b).yield{|fb| a = fb if fb}


Shades of forth:

class Object; def if?; yield(self) if self end end

a = 1
"fred wilma"[/fred/].if?{|x| a = x}
p a # ==> "fred"
"fred wilma"[/barney/].if?{|x| a = x}
p a # ==> "fred"


Btw, I think this construct has appeared before, but I can't seem to 
recall what it was called...

-- 
       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407