From: Robert Klemme <bob.news@...>
Date: 2004-06-14T20:43:39+09:00
Subject: Re: undefine


"Christoph" <chr_mail@gmx.net> schrieb im Newsbeitrag
news:2j4ab0FskcpcU1@uni-berlin.de...
> tony summerfelt wrote:
> ...
> > in my particular case i'm thinking black box approach. i don't want
> > the variable to 'exist' any more.
> >
> > i don't know if that's how it's thought of in perl, but when i
> > undef($x), $x is no longer there for me to use unless i assign it
> > something, and i can test that it isn't with:
> >
> >  if ! defined($x) # do something.
> >
> > as long as ruby 'acts' the same way, it's all i need.
>
> I am aware of this kind of functionality for
> instance and class variables - for local or
> global variables such methods, afaik (I am not
> really sure!!!) don't exist.
> I see no problems with a removal method
> for global variables but we are probably better
> off without removal methods for local variables.

What do you gain by undefining instance variables?  If you access it via
@foo it'll be nil anyway.

Regards

    robert

>
>
> ---
> class A
> @x = 1
> @@x = 1
> $x = 1
> x = 1
> remove_instance_variable :@x
> remove_class_variable :@@x
> begin
> remove_gobal_variable :$x
> rescue => mes
>   puts mes
> end
>
> begin
>   remove_local_variable :x
> rescue => mes
>   puts mes
> end
> end
> ---
> undefined method `remove_gobal_variable' for A:Class
> undefined method `remove_local_variable' for A:Class
> ---
>
>
> /Christoph