From: Joel VanderWerf <vjoel@...>
Date: 2009-08-12T05:17:30+09:00
Subject: Re: Dynamically creating a multi dimensional hash

David Sainte-claire wrote:
> Hello,
> 
> I am trying to do something that on the surface seems easy, but in
> practice I don't have a clue how to approach it.  I need to create a
> multi-dimensional hash to represent certain attributes of a particular
> item.  When I hardcode the hash for testing purposes it looks something
> like this:
> 
> @skuList = [{:sku => "XXXX", :price => "$ZZZZ.ZZ"}, {:sku => "YYYY",
> :price => "$AAA.AA"}]
> 
> However, in production I need to be able to generate an almost exact
> same hash dynamically, with the exception of that I don't know how many
> objects will need to be inserted into the hash.
> 
> Basically, I will be reading in a file that contains an unknown number
> of item names and need to return  hash that contains the above
> attributes for all entries in the file that I just read.
> 
> Unfortunately, I am very new to Ruby, and don't have a clue where to
> start on something like this.
> 
> Can someone help me out?
> 
> Thanks,
> David

Looks like an array of hashes. What do you mean by "multidimensional hash"?

There's a ruby idiom that may or may not apply here, making use of the 
default proc of a hash to create arbitrary nesting:

make_hash = proc do |hash,key|
   hash[key] = Hash.new(&make_hash)
end

h = Hash.new(&make_hash)

h[1][2][3] = "foo"

p h # => {1=>{2=>{3=>"foo"}}}

But if you are just trying to construct an array of hashes, something 
like this may work:

ary = []
File.open(...).each do |line|
   hash = your_parser(line)
   ary << hash
end

Sorry if I've misunderstood!

-- 
       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407