On 4/22/05, Robert Klemme <bob.news / gmx.net> wrote:
> 
> 
> Class variables are really only useful if you want to access them from
> instances and from the class in a similar way (via "@@var_name").
> Otherwise they have more drawbacks than pros so I avoid to use them
> whenever I can.  (Can't really remember a case where I actually needed
> them.)
> 
What about situations like the following ( taken from an attempt at an
old rubyquiz )

class Op
    @@lookup = {}
    def Op.register(newOp, newOpClass)
       @@lookup[newOp] = newOpClass
    end
end

class AddOp < Op
...
end
class SubOp < Op
...
end
class MulOp < Op
...
end
class DivOp < Op
...
end

Op.register("+", AddOp)
Op.register("-", SubOp)
Op.register("*", MulOp)
Op.register("/", DivOp)

They are not really OO 'clean' but better than globals surely?


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