From: "David A. Black" <dblack@...>
Date: 2004-09-03T22:08:03+09:00
Subject: Re: [Design advice] including a file as code ('as is')

Hi --

On Fri, 3 Sep 2004, Benny wrote:

> dear list,
> 
> I have 2 files: main.rb and include_me.rb.
> I want include_me.rb to contain only the method definitions 
> (dont have to care about its module and class).
> 
> [[background information: 
> the real problem is a bit more complicated.
> finally 'main.rb' will open lots of different 'include_me.rb's in a loop
> and even check if it has already opened them before open them twice, but
> running classname.run each time in the loop (i.e. file name of the include
> and classname are variables passed to main.rb in the loop)]]
> 
> 
> the following code works, but
>         - will it always work no matter whats in 'include_me.rb'?
>         - is there a better solution to get rid of the evil "eval"?
> 
> I know there is send(:define_method, "method_name") but I want
> 'include_me.rb' to appear like if it would be a valid ruby script on its
> own (without using any "special methods" only for the inclusion purpose).
> 
> to simply redefine the same class in each include file is not an option.
> 
> regards,
> 
> benny
> 
> ####### here comes the pseudo code #########
> 
> # main.rb
> module My_Module
>         class MyTest
>                 def initialize(str)
>                         puts "initializing: #{str}"
>                 end
>                 lines = [] 
>                 File.open('include_me.rb').each_line{ |line |
>                         lines << line
>                 }               
>                 eval(lines.join(';'))

I know you want to avoid eval, but as long as it's here, just to show
you a somewhat shorter way to eval the contents of a file:

   eval(File.read("include_me.rb"))

(Ruby really is good at doing things like that concisely :-)

Anyway, as for another way: you could just 'require' the file,
although then you end up with the methods being private.  But if you
know what they're called that may be not a big problem:

  module MyModule
    class MyTest
      def initialize(str)
        puts "initialize: #{str}"
        require "include_me.rb"
        self.class.class_eval { public :run }
      end
    end
  end

etc.


David

-- 
David A. Black
dblack@wobblini.net