From: Chris Pine <nemo@...>
Date: 2002-12-12T03:51:19+09:00
Subject: Re: deleting a class

Here's something weird:

If instead of using the code:

  class Foo
  end

...I instead use...

  eval 'class Foo; end'

...then the rest of the code *does* delete the class!

I just went through all of that in my mail "all the pretty evals..."; I was
asking if these are the same.  Obviously they aren't the same.

So what's the difference?  And what about the other evals:  do they work
like 'eval' does?  What about 'require' and 'load'?  (Those last two were
rhetorical questions; I can figure it out on my own.  I just want to know
what the difference is and why it works this way.)

Chris



----- Original Message -----
From: "Chris Pine" <nemo@hellotree.com>
Newsgroups: comp.lang.ruby
Sent: Wednesday, December 11, 2002 10:20 AM
Subject: deleting a class


Hello,

I'm try to find a way to completely delete a class.  (What I would
eventually like is a way to load an entire GUI by default, but if the user
requests a new one, I'd like to unload the old one and load up the new one.)

So, in this code I create class Foo, but I can't figure out how to delete
it.  Am I doing the GC wrong, or is there some reference to Foo I haven't
yet deleted?  Or both?


  def getAllClasses
    classes = []
    ObjectSpace.each_object (Class) do |klass|
      classes << klass.to_s
    end
    classes
  end

  def getAllConstants
    Module.constants
  end

  originalClasses   = getAllClasses
  originalConstants = getAllConstants

  class Foo
  end

  Object.module_eval { remove_const 'Foo' }

  GC.start

  puts 'New classes:    '+(getAllClasses   - originalClasses  ).join(', ')
  puts 'New constants:  '+(getAllConstants - originalConstants).join(', ')


Thanks for any help you can offer,

Chris