From: Benjamin Kudria <ben@...>
Date: 2010-07-08T13:18:44+09:00
Subject: Re: Extending OpenStruct to be lazy and recursive

Michael Jackson wrote:
> I've done something similar that's pretty lightweight. My version
> actually extends Hash, so it should be pretty fast and you get all the
> niceties of Hash for free.

Michael, thanks for the pointer, but I don't really see how it helps. 
Your code doesn't support recursive conversion, or lazy property 
retrieval. I'm content with using OpenStruct for all the functionality 
your code provides.

Thomas Sawyer wrote:
> 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.

Indeed, my initial version didn't use mental's library, but I had to 
reach way deeper into OpenStruct to make the appropriate changes.

OpenCascade is awesome! But,I left out a small detail of my 
implementation that is actually rather important - my to_self method 
actually tries to find a class corresponding to the name of the key (the 
.classify.constantize call) and use that if available. So, {:authors => 
[{:name => 'Poe'}, {:name => 'Lovecraft'}]} would actually end up 
converting to two Author objects, if the class were available, passing 
the hash to the initialize method. This functionality is important to 
me, it allows me to hang business logic on sub-documents in my overall 
document. OpenCascade, it seems, converts only to OpenCascade.

(I may take a detour and subclass OpenCascade instead, modify it to 
support my auto-classifying,, and compare the two approaches.)

Fortunately, mental clued me into the problem with my code [1] shortly 
after I posted this. For future reference, I was creating the promise 
(with its associated block) and closing over the same k and v variables, 
instead of creating a new scope every time. I separated the call out to 
a method, and everything worked.

Benjamin Kudria
ben@kudria.net

1: http://twitter.com/mentalguy/status/17993170022 and 
http://twitter.com/mentalguy/status/17993202421
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