From: ES <ruby-ml@...>
Date: 2005-02-20T07:07:15+09:00
Subject: Re: Dynamically loading and executing within a new module?


On 2/19/2005, "Lloyd Zusman" <ljz@asfast.com> wrote:

>I'm not sure what would be the best way to accomplish the following in
>ruby:
>
>I'm writing a program that periodically looks for files in a certain
>directory.  If it finds new ones, I want it to ...
>
>1. Dynamically create a new module whose name is based somehow upon the
>   name of the file.
>
>2. Do a Kernel#load on the file within this newly created module.
>
>3. Invoke a method called #init that is defined in this file (assuming
>   that this method is actually defined), and do the invocation within
>   the context of that newly-created module.
>
>For example, suppose my directory contains the following files:
>
>  foo.module
>  ----------
>  def init
>    puts "invoking #init within #{self}"
>  end
>
>  bar.module
>  ----------
>  def init
>    puts "invoking #init within #{self}"
>  end
>
>When my program encounters the "foo.module" file, I'd like it to do the
>following:
>
>  - create a module called Foo (the name of the file with ".module"
>    stripped off and the first letter capitalized) ... or maybe
>    SomethingElse::Foo, to avoid collisions with existing packages
>
>  - do a load() of the "foo.module" file within the context of this
>    newly created Foo module (or SomethingElse::Foo module)
>
>  - check to see if the #init method is now defined within the
>    Foo module; if so, invoke that as a class method within the
>    context of that module (i.e., as if it were invoked like
>    Foo#init); this should cause the following message to
>    print:
>
>      invoking #init within Foo
>
>What is the recommended way for accomplishing all this within Ruby?

If you don't just want to write an actual module and then call its #init,
you could do something like this. Somewhat pseudo:

Thread.new do
  if fname
    mod = eval fname.capitalize
    data = File.new(fname, 'r') do |f|
             f.read
           end
    mod.module_eval data
    mod.send :init, args
    # ...
  end
end

Or sumptin :)

> Lloyd Zusman

E