From: Isaac Sanders <isaacbfsanders@...>
Date: 2011-11-07T07:47:50+09:00
Subject: Re: Tricky DSL, how to do it?

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You are missing a `super` on the method_missing. first you should ask if is
a method on the class, and if it is, call super with no args.
try:
class Evaluator < BasicObject
    def initialize(&block)
      @__config__ = {}
      instance_eval(&block) if block
    end

    def __config__
      @__config__
    end

    def method_missing(sym, *args, &block)
      respond_to? sym ? super : @__config__[sym] = block
    end
  end


On Sun, Nov 6, 2011 at 5:35 PM, Intransition <transfire@gmail.com> wrote

> I'd want to write a DSL such that a surface method_missing catches
> undefined methods and records the blocks that they define e.g.
>
>   foo do
>     puts "foo"
>   end
>
> So I would end up with:
>
>   { :foo=>#<Proc ...> }
>
> Presently I have something like this:
>
>   #
>   class Evaluator < BasicObject
>     def initialize(&block)
>       @__config__ = {}
>       instance_eval(&block) if block
>     end
>
>     def __config__
>       @__config__
>     end
>
>     def method_missing(sym, *args, &block)
>       @__config__[sym] = block
>     end
>   end
>
> However when I call on a block I want it to evaluate as if in the defining
> context (in this case toplevel), not inside the "DSL" class that evaluated
> via method_missing.
>
>   e = Evaluator.new do
>     foo do
>       puts "foo"
>     end
>   end
>
>   e.__config__[:foo].call
>
> Instead of what I want, I get a method missing error for #puts.
>
> Any ideas?
>



-- 
Sincerely,

Isaac Sanders
Section C-4B Vice Chief, Order of the Arrow
Vice Chief of Administration, Tecumseh #65
Eagle Scout

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