From: Gavin Kistner <gavin@...>
Date: 2005-05-27T12:08:58+09:00
Subject: [ANN] Finite State Ma-thing 0.6

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Announcing the "Finite State Ma-thing", a base class to make it easy  
to implement a state-machine-like jobber.

'Tis a simple class at the core, but a powerful abstraction. (Ruby is  
so good at that.)


See the documentation (with pretty picture!) at http://phrogz.net/ 
RubyLibs/FiniteStateMathing/, which also has a link to the full  
source code, and includes an example.

I used this as a proof-of-concept for a half-assed XML parser (behold  
the horror! at http://phrogz.net/tmp/XML_FSM.png), that sort of acts  
like a SAX parser. I don't know much about Finite State Machines or  
their theory, but the beauty of the solutions that FiniteStateMathing  
allows is that you _mostly_ use state to figure out what to do, but  
also have all the power of instance variables and methods at your  
disposal to help you along.

Because I wanted to allow _any_ object as a state, and because I  
could not find a way to invoke a class-scoped block to be executed  
(with parameter) in the scope of the instance, I'm using the  
#define_method hack suggested by Pit Captain, made uglier by me  
because (for uniqueness) all the method names are based off of the  
#object_id of the state.

This class was mostly an educational exercise for me. Please help  
further my education: gimme a holla if you see inefficiencies, have  
suggestions for cleaner ways to implement existing code, or envision  
cool features or cleaner interfaces.

Enjoy!

--
"When I am working on a problem I never think about beauty. I only  
think about how to solve the problem. But when I have finished, if  
the solution is not beautiful, I know it is wrong."
- R. Buckminster Fuller


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