From: "m4rkusha@..." <m4rkusha@...>
Date: 2006-02-16T21:48:32+09:00
Subject: Re: Creating objects without knowing their names

Robert Klemme wrote:
> Joel VanderWerf wrote:
> > paul.p.carey@gmail.com wrote:
> >> Hi
> >>
> >> I'd like to load an arbitary number of Ruby files from a directory
> >> and create their associated objects. However, I don't know the class
> >> names of the files that have just been loaded. Is it possible to
> >> determine a file's class name once that file has been loaded?
> >> (Without resorting to parsing, or enforcing a mapping between the
> >> filename and class name.)
>
> > You probably know this already, but for the benefit of bystanders:
> > there isn't in general one-to-one mapping between classes and files.
> > A class
> > can be defined across several files; a file can contain several class
> > definitions. (Maybe in the case of the files you are using there is
> > always a 1-1 map, though.)
>
> There are other options.  Some of them:
>
>  - Make sure all classes on those files inherit a base class which
> overrides #inherited so it gets notified every time a sub class is
> created.  You can then store the set of sub classes in a member of the
> base class and use that for whatever purposes.
>
>  - Make classes in those files register with some arbitrary registry you
> create (that's basically the same as the first just more explicit).
>
>  - use set_trace_func to trance execution of those files and notice
> whenever a new class occurs.  (Not sure whether that works though).
>
> Kind regards
>
>     robert

Or you can compare the classes you had before loading to classes you
had after loading. Something like this:

def defined_classes
    classes = []
    ObjectSpace.each_object(Class){|c| classes << c}
    classes
end

initial_classes = defined_classes
require 'net/http'
p defined_classes - initial_classes