From: Intransition <transfire@...>
Date: 2010-07-08T10:39:18+09:00
Subject: Re: Extending OpenStruct to be lazy and recursive



On Jul 7, 8:29 pm, Benjamin Kudria <b...@kudria.net> wrote:
> I'm trying to extend OpenStruct for an application I'm building, where
> I'd like to access nested hashes as models. OpenStruct (in core) sounds
> perfect for this, but I ran into two problems:
>
>  - Recursion
>     My hashes have nested hashes, and I want to convert *those* to
> objects, too. I was able to solve this problem pretty easily, see the
> to_self method in the linked code [1].
>
> However, this made me run into the second problem - speed. I was loading
> rather large documents, and it was taking quite a bit of time to go
> through them, instantiating classes for everything. I though I'd make
> the code lazy-load, using the lazy.rb [0]
>
> However, I overrode some more core methods for OpenStruct, to create
> promises, and demand them, but now the code simply produces incorrect
> results.
>
> In IRB, I do:
>
> > LazyStruct.new({:a=>1, :b => 2}).a
>
> But my result is 2, not 1. The code is here:http://gist.github.com/467459
>
> What could be going wrong? Any inishgt would be appreciatted. I'm using
> Ruby 1.9.2-preview3

Not 100%, but maybe have a look at Hashery's OpenCascade for some
ideas (http://rubyworks.github.com/hashery). I think you can do the
lazy lookup without using a Promise.