From: Ken Bloom <kbloom@...>
Date: 2007-11-04T10:40:03+09:00
Subject: Re: x=[]; x[:bla][:some_key] does not work?

On Sat, 03 Nov 2007 15:44:48 -0500, sepp2k wrote:

> Joshua Muheim wrote:
>> PHP lets me easily create multidimensional hashes[...] Is Ruby not
>> capable of doing this?
>>
>> x = []
> 
> That's an array. A hash would be x={}
> 
>> x[:bla][:some_key] = true
>>
>> gives me a nil error!
> 
> The code above should give you a different error. If you use {} it
> should give you a nil error because x[:bla] would return nil and nil
> doesn't have a method [].
> To fix that you have to make x return a hash for non-existant keys. That
> would work as such:
> x = Hash.new {|h,k| h[k] = Hash.new}
> x[:bla][:some_key] = true
> 
> Or if you want an arbitrary amount of nesting:
> 
> blk = lambda {|h,k| h[k] = Hash.new(&blk)} x = Hash.new(&blk)
> x[:la][:li][:lu][:chunky][:bacon][:foo] = "bar"
> 
> 
> HTH,
> Sebastian

Or use Hash#autonew from the facets gem, which does precisely the same 
thing.

--Ken

-- 
Ken Bloom. PhD candidate. Linguistic Cognition Laboratory.
Department of Computer Science. Illinois Institute of Technology.
http://www.iit.edu/~kbloom1/