From: dblack@...
Date: 2007-06-12T04:38:49+09:00
Subject: Re: Constants and metaclasses

Hi --

On Tue, 12 Jun 2007, Andreas Launila wrote:

> Is there a way to define a constant in a metaclass and then have it used
> in methods defined in the original class?
>
> An example:
>
>
> class Foo
>  def foo
>    p BAR
>  end
> end
>
> f = Foo.new
> class <<f
>  BAR = "Hello"
>
>  def bar
>    p BAR
>  end
> end
>
> f.bar
> f.foo
>
>
> The line "f.bar" will work fine, but "f.foo" will fail with "NameError:
> uninitialized constant Foo::BAR". Is there some way to have the method
> defined in the original class pick up on the constant in the metaclass
> (without altering "p BAR")?

I don't think so (and I hope not, as it would be kind of strange :-)
but you could define BAR in the original class:

   class << f
      Foo::BAR = "Hello"

etc.


David

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