From: James Edward Gray II <james@...>
Date: 2007-11-27T04:33:16+09:00
Subject: Re: module_eval is an instance method?

On Nov 25, 2007, at 11:43 PM, 7stud -- wrote:

> Paul McMahon wrote:
>> module_eval is a instance method of Module.
>>
>> It is available to anything that is a Module.
>>
>> irb(main):001:0> Object.is_a?(Module)
>> => true
>> irb(main):002:0> String.is_a?(Module)
>> => true
>> irb(main):003:0> self.is_a?(Module)
>> => false
>
> Ok, how do you explain this output:
>
> def meth1
>   Object.module_eval('num')
> end
>
> num = 10
> Object.module_eval('num')
> -->10
>
> meth1
> -->
> `module_eval': undefined local variable or method `num' for  
> Object:Class
> (NameError)
>
> According to pickaxe2, p. 393:
>
> "When we define methods, we're actually creating (private) instance
> methods for class Object."

Ruby pretty much says exactly what's going here:  num is not a local  
variable or a method *accessible inside the scope of meth1.*

> What about top level variables?

I don't reccomend this, but you can get at them:

#!/usr/bin/env ruby -wKU

def print_num
   puts eval("num", TOPLEVEL_BINDING)
end

num = 10
print_num

__END__

James Edward Gray II