From: Sean Chittenden <sean-ruby-talk@...>
Date: 2001-07-11T17:00:52+09:00
Subject: [ruby-talk:17641] Re: Hash as an instance variable...


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	This makes complete sense and was what I thought was happening. =20
None-the-less it was still a decent gotcha that I wasn't expecting. =20
This was a very helpful response, thank you.  Maybe this code snippet=20
could make its way into the next Programming Ruby book.  ;~)  -sc

> > class Testing
> >   @test_hash =3D Hash.new()
> >=20
> >   public
> >   def set(key, val)
> >     @test_hash[key] =3D val
> >   end
> > end
>=20
> That's a Java idiom that doesn't mean the same thing in Ruby.  In a class
> definition, outside of a method definition, you are in the context of the
> *class* object, not the instance.  So what you're doing there is defining
> a class instance variable (sort of, but not really at all, like a static
> variable in Java), whereas when you did it inside the initialize method
> you were defining an instance variable.
>=20
> This is confusing.  The short answer is, do it in the initialize instead.
>=20
> For a start at the long answer, try this:
>=20
> class Testing
>=20
> 	@var =3D "class"
> =09
> 	def initialize
> 		@var =3D "instance"
> 	end
>=20
> 	def Testing.print
> 		puts @var
> 	end
>=20
> 	def print
> 		puts @var
> 	end
> end
>=20
> t =3D Testing.new
> t.print
> Testing.print



--=20
Sean Chittenden

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