From: Philipp Meier <meier@...>
Date: 2002-09-04T00:53:17+09:00
Subject: Class variables and inheritance


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Hallo rubyers,

I'm a little puzzled with Class variables (@@foo) and inheritance:

class Super
	@@foo =3D []

	def self.manipulate(arg)
		@@foo << arg
	end

	def get_foo
		@@foo
	end
end

class Sub1 < Super

	manipulate "first"

end

class Sub2 < Super
	manipulate "second"
end

Sub1.new.get_foo # =3D> ["first","second"], wanted "first"
Sub2.new.get_foo # =3D> ["first","second"], wanted "second"

I know that Class variables a tied to the class they are defined in but
how can I make @@foo belong to Sub1 / Sub2 without explicitly declaring
it there?=20

I tried append_features which worked partly:

module Super
	def self.append_features(klass)
		class << klass
			@@foo =3D []

			def manipulate(arg)
				@@foo << arg
			end
		end
	end
end

class Sub1
	include Super
end

But then, how can a declare an instance method? I don't like to do both
inheritance and including a Mixin which should work at the end:

class Sub1 < SuperClass
	include SuperModule
end

Any help is appreciated.

-billy.

--=20
Meisterbohne       S=F6flinger Stra=DFe 100          Tel: +49-731-399 499-0
   eL=F6sungen       89077 Ulm                     Fax: +49-731-399 499-9

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