From: "Kroeger, Simon (ext)" <simon.kroeger.ext@...>
Date: 2006-04-13T21:58:47+09:00
Subject: Re: map_if, collect_if ???

> > module Enumerable
> >     def map_if( &block )
> >         find_all(&block).map(&block)
> >     end
> > end
> [...]
> I will file away the find_all  {}.map {} idiom for future use 
> [...]

I would change that to:

    map(&block).select{|e|e}

there can be surprising side effects if the user doesn't 
expect the block to be called twice for each element.

cheers

Simon