From: Gregory Brown <gregory.t.brown@...>
Date: 2007-07-06T07:20:15+09:00
Subject: Re: Calling an arbitrary method as and when an array's contents change

On 7/5/07, Dan Stevens (IAmAI) <dan.stevens.iamai@gmail.com> wrote:
> I have a collection class that extends the Array class and I wish to
> have a particular method to be called whenever the contents of an
> instance of the class change. Can anyone advise on how I can achieve
> this?
>
> I'm aware that I can compare #hash with a previous saved value to
> determine if the contents of the instance have changed since the last
> time #hash was called. Therefore, if I can find a means of calling an
> arbitrary method or piece of code every time any method is called on
> the instance, I could achieve what I'm after. Can I override
> Object#send?

It sounds like you might be able to set up something like this with Observer.
http://www.ruby-doc.org/stdlib/libdoc/observer/rdoc/index.html