From: Anatol Pomozov <anatol.pomozov@...>
Date: 2005-08-26T22:12:26+09:00
Subject: Re: Circular dependecy on classes

Thanks for your quick answers.

Somewhere (i did not remember) I saw following trick

def Soldier
  @can_upgrade_to = [:Knight] #This list != list of all ancestors

  def upgrade?(to)
     @can_upgrade_to.include?(to.to_s.to_sym)   
  end
end

but the solution provided by Derek seems more natural for me.

Thanks to all.
On 8/26/05, Derek Wyatt <derek@derekwyatt.org> wrote:
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> 
> I think you're simply using an instance variable where a method is
> what you want.  Take advantage of the runtime compile/binding that
> you're currently having problems with.  Do this instead:
> 
> class Solder
> ~  def can_upgrade_to
> ~    [Knight]
> ~  end
> end
> 
> And your problems go away.  You don't have to open it up later.  If
> you want it private, you can simply make it private.
> 
> Regs,
> D
> 
> Anatol Pomozov wrote:
> | I have several classes that have circular dependencies on each other.
> | See following example.
> |
> | class Solder
> |   @can_upgrade_to = [Knight]
> |   #or use constant from Knight class
> |
> |   def upgrade!(to)
> |     raise "Unable to upgrade" unless @can_upgrade_to.contain(to)
> |   end
> | end
> |
> | class Knight < Solder
> | end
> |
> | I cant use Knight constant (class name) before Solder and can't use
> | Solder before Knight.
> |
> | I am just come from Java lang and for Java circular class deps is not
> | a problem.
> | But ruby is a dynamic language and it creates classes just on script
> | executing. (right?)
> |
> | So my questions is: how to solve this problem? What is the best way to
> | deal with it.
> |
> 
> 
> - --
> Derek Wyatt - C++ / Ruby / Unix Programmer
> http://derekwyatt.org
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-- 
anatol