From: William James <w_a_x_man@...>
Date: 2006-11-16T02:30:37+09:00
Subject: Re: Design problem with 'inject'


Gary Boone wrote:
> Ruby's inject has a design that can lead to hard to find bugs. The
> problem is that you don't have to specify what is summed; the value of
> the block is summed. That means 'next' can lead to a bug. Here's an
> example:
>
> No problem:
>
>    arr.inject(0) do |sum, i|
>                     sum += i
>                  done
>
> But suppose you need to skip some elements, so you add a 'next'
> statement.
> Problem:
>
>    arr.inject(0) do |sum, i|
>                    next if (i==3)
>                    sum += i
>                  done
> 

[1,2,3,4,5].reject{|n| n==3}.inject{|s,n| s+n}