From: Stefan Rusterholz <apeiros@...>
Date: 2008-10-27T16:21:09+09:00
Subject: Re: Hash.merge_add! extension - how does this code look?

Greg Hauptmann wrote:
> thanks for highlighting this!  Is the quickest way to normalise to Array 
> via
> the following?
>     hashitem.instance_of?(Array) ? hashitem : [hashitem]

If you're building up the hash yourself then I'd use the following 
idiom:
collector = Hash.new { |h,k| h[k] = [] }
collector['key1'] << 'value1'
collector['key2'] << 'value1'
collector['key1'] << 'value2'
p collector

Simplifies adding to and reading from the hash. But be aware that with 
the hash having a different default value than nil, you can't use 'if 
collector[key] then' to test for existence of a key anymore, you have to 
use has_key?.

If you're not building the hash up yourself, then yes, I'd use what you 
wroten in an each loop and override the existing value.

Regards
Stefan
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