ruby: how to load .rb file in the local context

Question

How this simple task can be done in Ruby?
I have some simple config file

=== config.rb
config = { 'var' => 'val' }

I want to load config file from some method, defined in main.rb file so that the local variables from config.rb became local vars of that method.
Something like this:

=== main.rb
Class App
    def loader
        load('config.rb') # or smth like that
        p config['var']   # => "val"
    end
end

I know that i can use global vars in config.rb and then undefine them when done, but i hope there's a ruby way )

Answer 1

You certainly could hack out a solution using eval and File.read, but the fact this is hard should give you a signal that this is not a ruby-like way to solve the problem you have. Two alternative designs would be using yaml for your config api, or defining a simple dsl.

The YAML case is the easiest, you'd simply have something like this in main.rb:

Class App
  def loader
      config = YAML.load('config.yml')
      p config['var']   # => "val"
  end
end

and your config file would look like:

--- 
var: val

Answer 2

I do NOT recommend doing this except in a controlled environment.

Save a module to a file with a predetermined name that defines an initialize and run_it methods. For this example I used test.rb as the filename:

module Test
  @@classvar = 'Hello'
  def initialize
    @who = 'me'
  end

  def get_who
    @who
  end

  def run_it
    print "#{@@classvar} #{get_who()}"
  end
end

Then write a simple app to load and execute it:

require 'test'

class Foo
  include Test
end

END {
  Foo.new.run_it
}

# >> Hello me

Just because you can do something doesn't mean you should. I cannot think of a reason I'd do it in production and only show it here as a curiosity and proof-of-concept. Making this available to unknown people would be a good way to get your machine hacked because the code could do anything the owning account could do.