From: Bill <ruby@...>
Date: 2005-06-06T02:15:25+09:00
Subject: Re: Creating objects from strings.

On 2005-06-05 09:51:42 -0400, James Britt <james_b@neurogami.com> said:

> Bill wrote:
>> Hi,
>> 
>> I'm a Java programmer that is trying to learn Ruby.
>> 
>> I'm trying to write a container that creates objects on the fly from a 
>> descriptor.  In Java I'd simply do 
>> Class.forName("MyClass").newInstance();
> 
> 
> mc = Object.const_get( "MyClass" ).new
> 
> This presumes that the code already knows about the class MyClass 
> (e.g., because the class is defined in the same file, or defined in a 
> file that has already been read using 'require' or 'load').
> 
> 
> 
> BTW, I  looked at the Ruby FAQ, and this question doesn't seem to be in 
> there, despite its popularity.
> 
> http://dev.rubycentral.com/faq/
> 
> 
> 
> James

Thanks for all the quick help.  The presumption was my problem.  I had 
some code that I got that should have worked, but wasn't requiring the 
file.  I'm now able to create classes from external files/modules with 
the following.

  def load (filename, classname)

    require filename

    # taken from http://www.ruby-talk.org/cgi-bin/scat.rb/ruby/ruby-talk/9295
    names = classname.split /::/
    names.reverse!
    unf = Object
    unf = unf.const_get(names.pop) while names.length > 0
    unf.new
  end

load ("myfile.rb", "myModule::myClass")