From: Jimi Damon <jdamon@...>
Date: 2007-12-08T09:00:16+09:00
Subject: Re: Problem with Hash of Arrays

Bernardo Rufino wrote:
> In addition, to create different Arrays objects use a block...
> 
> irb(main):001:0> a = Hash.new{|hash, key| hash[key] = Array.new;}
> => {}
> irb(main):002:0> a[:first]
> => []
> irb(main):003:0> a[:first] << "test"
> => ["test"]

Yes, but if you run this example and type "a" you get

irb(main):003:0> a
=> {}

I'm sorry...but I think this is incorrect... You have defined an array 
as being the default type , hence after
you have performed  << "test" ,   a should contain

=> {:first=>["test"]}

But it does not..


As for the other post.

When you define   Hash.new(  ) , this is the default value when you HAVE 
NOT defined the key for that value.

Hence, if I do

a = Hash.new("tmp")

and type in irb
irb(main):006 a = Hash.new("tmp")
=> {}
irb(main):007 a[:first]
=> "tmp"
irb(main):008 a
=> {}
irb(main):009

This makes sense because it is accessing the default value for the key 
which is "tmp"

However, with that being said, if my default type is an "array", then I 
should be able to Push into that array a value and have it stay around, 
other wise why does

a[:key] += ["value"]
and then
a[:key].push("another value")
work ?









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