From: Eero Saynatkari <eero.saynatkari@...>
Date: 2006-08-30T09:23:18+09:00
Subject: Re: Hash#inject argument syntax

Brian Buckley wrote:
> The code below works but I do not understand the  "(key, value)"
> parenthesis syntax.  I have not seen it before.  Could someone
> explain?
> 
> --Brian
> 
> (from Rails' active_support)
> class Hash
> def symbolize_keys
>    inject({}) do |options, (key, value)|

Hash#each, as you may know, actually produces an Array
of Arrays (key-value pairs). Here what is being passed
is actually one of those pairs--the parenthesised syntax
uses Ruby's assignment rules and splats the Array to
two distinct variables. Consider it the same as:

 key, value = ['key', 'value']

>     options[key.to_sym] = value
>     options
>   end
> end
> end
> (above code from Rails' active_support)


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