From: Jos Backus <jos@...>
Date: 2008-02-20T07:28:23+09:00
Subject: Re: ||= [] idiom

On Wed, Feb 20, 2008 at 07:11:31AM +0900, Leslie Viljoen wrote:
> I often make use of this idiom to add something to an array in a hash of arrays:
> 
> @categories = {}
> 
> pagelist.each do |resource|
>     @categories[resource.tag] ||= []
>     @categories[resource.tag] << resource
> end

@categories = {}

pagelist.each do |resource|
    (@categories[resource.tag] ||= []) << resource
end

or

@categories = Hash.new {|h, k| h[k] = []}

pagelist.each do |resource|
    @categories[resource.tag] << resource
end

-- 
Jos Backus
jos at catnook.com