From: Pat Maddox <pergesu@...>
Date: 2006-05-16T00:17:27+09:00
Subject: Weird class-loading issue (or maybe a problem with define_method?)

I'm working on an app and having a strange class loading problem.
I've extracted it to the most basic code possible.

# foo.rb
require "bar"
class Foo
  FOO = "foo"
end

# bar.rb
require "foo"
class Bar
  def self.set_foo(val)
    define_method(:foo) { val }
  end
end

class FooBar < Bar
  set_foo Foo::FOO
end

This works fine if I include bar.rb first:
baggio:~/work/test pergesu$ irb
irb(main):001:0> require "bar"
=> true

but it blows up if I do foo.rb:
irb(main):001:0> require "foo"
NameError: uninitialized constant FooBar::Foo
        from ./bar.rb:10
        from ./foo.rb:1
        from (irb):1

What's even more strange to me is that the FooBar class has no problem
accessing Foo::FOO from within a method, either class or instance:
class FooBar < Bar
  def foo; Foo::FOO; end
  def self.class_foo; Foo::FOO; end
end

irb(main):001:0> require "foo"
=> true
irb(main):002:0> FooBar.new.foo
=> "foo"
irb(main):003:0> FooBar.class_foo
=> "foo"

I've also moved self.class_foo into the Bar superclass, and there were
no problems.  The only issue that pops up then is when I write a class
method in Bar that ends up calling define_method passing in a constant
from the other file.  It only happens when I require "foo", but
require "bar" works fine.

Can anyone tell me what's going on here?  I really don't understand
it.  Also I've foundt that my program works if I require "bar" before
everything...but I don't like that solution.  Most classes don't even
know that that file ever gets required, so it feels ugly that I'd have
to require it at the beginning of every file I use.

Pat