From: Joshua Collins <josh@...>
Date: 2009-03-31T08:33:17+09:00
Subject: Re: When to use instance variables @

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Ah right.

I totally forgot about instance auto set to nil ;)

I see where you were coming from now.

On Mon, Mar 30, 2009 at 7:27 PM, I=F1aki Baz Castillo <ibc@aliax.net> wrote=
:

> El Martes 31 Marzo 2009, Joshua Collins escribi=F3:
> > All variables in Ruby (Local, Global, Instance (object), or Class) do n=
ot
> > need to be defined at the beginning of a method.
>
> I didn't say "at the beginning of a method", but "at the beginning of a
> class"
> (anyhow I was also wrong XD).
>
>
>
>
> > In Ruby, do you need to set that variable before calling it? Yes.
>
> Well, this is different for class variables and instance variables:
>
> --------------
> irb> @non_existing_instance_variable
> nil
>
> irb> @@non_existing_class_variable
> NameError: uninitialized class variable @@non_existing_class_variable in
> Object
>        from (irb):2
>        from /usr/bin/irb:12:in `<main>'
> --------------
>
> What I mean is that class variables MUST be defined (not declared, of
> course)
> before *reading* them, while an instance variable returns nil if it's not
> set
> yet.
>
>
>
> >           #No need to define the variable before it's value is set
> >           @@number_of_squares =3D 1
>
> Yes, please note that I said:
> ----------
> This is not true when using class variables (@@). These need to be
> "declared"
> at the beginning of the class
> ----------
> (note the "declared" between ""  XD)
>
>
> Regards.
>
>
> --
> I=F1aki Baz Castillo <ibc@aliax.net>
>
>

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