From: Mooffie n/a <mooffie@...>
Date: 2010-04-25T17:53:42+09:00
Subject: Re: DrX, an object inspector

David Masover wrote:
> On Wednesday 21 April 2010 11:20:12 pm Charles Oliver Nutter wrote:
> > ref.class # now org.jruby.RubyString
> > ref.methods # now includes all Java-land methods on RubyString
> > cls = ref.metaclass # an org.jruby.RubyClass instance
> > cls.methods # should be the internal method table
>
> It seems like this should be possible to do from bare Ruby, in a 
> portable way.
> Clumsy, but possible. 

How, for example, can you find an object's class using pure Ruby?

The problem with Ruby's #class is that it skips singletons. Example:

  s = "blah"
  def s.whatever; 666; end
  p s.class

The above will print "String", but it's an error: the class should be 
some singleton.

(Doing "class << s; self; end" isn't a solution because it alters the 
object model: it *creates* a singleton if none yet exists.)

Though maybe there *is* a way to find an object's class, I don't know (I 
still consider myself a Ruby newbie).


> > cls.methods # should be the internal method table
>
> It seems like this should be possible to do from bare Ruby, in a 
> portable way.

As another example, consider this:

  module M
    def whatever; 666; end
    undef_method :whatever
  end

M.instance_methods() won't report the method 'whatever', whereas Ruby 
keeps a stub under that name. I want to see it.

When I started writing DrX my intention was to figure out how Ruby 
and/or MRI works. So high-fidelity was important to me. In fact, I 
simply wanted to see the C structures. I'm not interested in 
approximation.

(Though nothing prevents replacing the C extension with a pure-Ruby 
implementation.)
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