From: James Gray <james@...>
Date: 2008-01-10T03:25:40+09:00
Subject: Re: using ruby for config files

On Jan 9, 2008, at 11:35 AM, furtive.clown@gmail.com wrote:

> On Jan 9, 9:44 am, Karl von Laudermann <doodpa...@mailinator.com>
> wrote:
>>
>> If you just want to have configuration files that are little more  
>> than
>> key/value pairs, why not use the Windows INI file format? There are
>> already ruby gems that provide read/write access to INI files:
>
> Because using XML, YAML, or INI files robs me of the occasional #map,
> for instance, as shown in my example.  The whole point is that I
> *don't* want configuration files that are little more than key/value
> pairs.  Even if that was the case at the beginning of the project,
> eventually it becomes too restrictive as the project grows.

I sometimes use the stupid simple:

#!/usr/bin/env ruby -wKU

require "ostruct"

module Config
   module_function

   def load_config_file(path)
     eval <<-END_CONFIG
     config = OpenStruct.new
     #{File.read(path)}
     config
     END_CONFIG
   end
end

__END__

Here are the tests:

#!/usr/bin/env ruby -wKU

require "test/unit"
require "tempfile"

require "config"

class TestConfig < Test::Unit::TestCase
   def test_config_returns_a_customized_ostruct
     assert_instance_of(OpenStruct, config)
   end

   def  
test_config_object_is_passed_into_the_file_and_used_to_set_options
     c = config(<<-END_SETTINGS)
     config.string_setting  = "just a String"
     config.integer_setting = 41
     END_SETTINGS
     assert_equal("just a String", c.string_setting)
     assert_equal(41,              c.integer_setting)
   end

   def test_exceptions_bubble_up_to_the_caller
     assert_raise(RuntimeError) do
       config(<<-END_ERROR)
       raise "Oops!"
       END_ERROR
     end
   end

   private

   def config(content = String.new)
     cf = Tempfile.new("ender_config_test")
     cf << content
     cf.flush
     Config.load_config_file(cf.path)
   end
end

__END__

James Edward Gray II