From: Glen Holcomb <damnbigman@...>
Date: 2010-01-26T04:24:53+09:00
Subject: Re: Nested hash with arrays for default value

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2010/1/25 Jes=FAs Gabriel y Gal=E1n <jgabrielygalan@gmail.com>

> On Mon, Jan 25, 2010 at 6:48 PM, Glen Holcomb <damnbigman@gmail.com>
> wrote:
> > I'm trying to find a "nice" way to make a nested hash with an empty arr=
ay
> as
> > the default "leaf" value.
> >
> > Basically I'd like to be able to make an assignment as follows:
> >
> >    data[2][3][4][5] << 3
> >
> > I can get close but I can't get it right.  The data is going to be comi=
ng
> > straight out of a log so I can't really build the hash ahead of time.
> >
> > --
> > "Hey brother Christian with your high and mighty errand, Your actions
> speak
> > so loud, I can=92t hear a word you=92re saying."
> >
> > -Greg Graffin (Bad Religion)
> >
>
> I've not tested this too much, but what I tried was to setup a proxy
> object that would insert a hash if the [] method is called on it, or
> an array if the << method was called:
>
> class ProxyDefault
>        def initialize hash, key
>                @hash =3D hash
>                @key =3D key
>        end
>
>        def [](key)
>                @hash[@key] =3D Hash.new {|hash,key| ProxyDefault.new(hash=
,
> key)}
>                @hash[@key][key]
>        end
>
>        def << value
>                @hash[@key] =3D []
>                @hash[@key] << value
>        end
> end
>
> h =3D Hash.new {|hash,value| ProxyDefault.new(hash, value)}
>
> h[1][2][3] << "value"
>
> p h
> p h[1][2][3]
>
> /temp$ ruby nested_hash_array.rb
> {1=3D>{2=3D>{3=3D>["value"]}}}
> ["value"]
>
> Hope this helps,
>
> Jesus.
>
>
Thanks Jesus,

I'll play around with your solution.  I have the following:

data =3D Hash.new { |l, k| l[k] =3D Hash.new { |l, k| l[k] =3D Hash.new { |=
l, k|
l[k] =3D Hash.new([]) }}}

Believe me I know it's ugly and not in any way flexible.  Plus it behaves i=
n
ways which make me uncomfortable when I try to print the contents.

--=20
"Hey brother Christian with your high and mighty errand, Your actions speak
so loud, I can=92t hear a word you=92re saying."

-Greg Graffin (Bad Religion)

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