From: Patrick Li <patrickli_2001@...>
Date: 2008-08-11T02:53:10+09:00
Subject: Re: DSL challenge. Do you guys have any elegant ideas?

Thanks for all the solutions.
I've looked through every one of them and here's my thoughts.

Joel VanderWerf: This is the ideal functionality. It's easily 
extendable. Very nicely object-oriented. And it was the first design 
that I actually used. Unfortunately, having to explicitly call the 
receiver object every time is not very elegant. Which lead to me using 
instance_eval to get around it.

The problem I was having with instance_eval is this:
instance_eval messes up your scope. Which is counterintuitive from the 
users point of view.

i.e. the user cannot call private helper methods from within Farm.create

def barnCreator
  barn do
    animal "Dog"
  end
end

Farm.create do
  barnCreator  #throws illegalmethoderror
end

Ara Howard: I think your solution solves the scope problems really 
nicely. Your code library is pretty advanced though. I'm going to need 
to understand it a little more fully before I can make a judgement.

Eric I: I notice that your manually controlling the "stack frame" to 
restrict access to certain methods. But you're using class_eval also, 
whose scope changes  will run into the same problems as instance_eval. 
I'm going to need to read through your code more carefully also to 
understand it.

So I guess the cleanest solution is still Joel's. But I just need a way 
to implicitly specify the receiver without changing scope and killing 
all my closures.

Thanks very much for your help guys. I definately learned a lot from 
your solutions.
  -Patrick
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