From: Helder Ribeiro <helder@...>
Date: 2007-06-11T14:42:39+09:00
Subject: Prettier solution to circular dependency

This is an aesthetic problem: I have a method in a module, and I want
to include it in three different classes (they're all in the same
file). This method refers itself to one of those classes. So i have to
include the module into the classes, but for the method to be parsed,
one of those classes needs to be already defined.

module ElementFactory
  def element_factory(what)
    (...)
    Element.new
  end
end

class Element
  include ElementFactory
  (...)
end

class Document
  include ElementFactory
  (...)
end

class ElementCollections
  include ElementFactory
  (...)
end


So for this class Element there's a circular dependency and, as ruby
does single-pass parsing, this can't work. What I've done so far is to
replace the explicit reference to Element in the module instance
method by a call to Object.const_get(:Element) so that when it's
called, Element will already be defined. But this looks a bit ugly.
isn't there a better way to solve this?

The circular dependency hints at not having the module at all and just
putting the instance method element_factory() into Element itself but
there are those other two classes that include it, so I can't do that.

Thanks a lot for any ideas! :-)


Cheers,

Helder


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