From: "ara.t.howard" <ara.t.howard@...>
Date: 2007-11-09T11:30:02+09:00
Subject: Re: local variables, eval, and parsing


On Nov 8, 2007, at 3:04 PM, furtive.clown@gmail.com wrote:

> Remember the motivation was to have a separate config file for these
> variables.  Unless ruby has something akin to the C-preprocessor
> #include then we are stuck with reading a file, which means we are
> stuck with a string, which means we are stuck with eval, which means
> we are stuck with ugly hacks in order to obtain local variables.


cfp:~ > cat a.rb
require "attributes" ### gem install attributes

class Config
   attribute "width"
   attribute "height"
   attribute "color"

   def self.load path
     config = new
     config.instance_eval IO.read(path)
     config
   end

   def configure &block
     instance_eval &block
   end
end

config = Config.load "b.rb"

p config

config.configure{ width 42.0 }

p config


cfp:~ > cat b.rb
configure {
   width 42

   height 42.0

   color "pinky-beige"
}


cfp:~ > ruby a.rb
#<Config:0x1ea3c @color="pinky-beige", @height=42.0, @width=42>
#<Config:0x1ea3c @color="pinky-beige", @height=42.0, @width=42.0>


it's true that they are not local vars but i think the effect is  
useful enough.


a @ http://codeforpeople.com/
--
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h.h. the 14th dalai lama