From: Stefano Cobianchi <stefano.cobianchi@...>
Date: 2007-08-04T05:50:00+09:00
Subject: Re: Running multiple closures per iteration

On Aug 3, 7:38 pm, Joshua Chia <joshc...@gmail.com> wrote:
> Is there a way to run more than one closure per iteration through a
> collection?  For example, if I want to do the following two things, can
> I combine them so that I only end up with one pass over the collection,
> without doing a manual for loop?
>
> o = a.select {|x| x >= 0}
> p = a.inject(0) {|s, x| s += x}

btw, you don't need the += operator here:
a.inject(0) {|s, x| s + x}
=> 6

> Such a combination is useful when iterating through a collection is
> expensive, e.g. on a large file on a slow disk.

o = 0; p = []
a.each { |x| o << x if x >= 0; p += x }

--
S.