From: niklas | brueckenschlaeger <niklas@...>
Date: 2010-11-29T01:24:36+09:00
Subject: Re: abstract classes and modules

--=-CAwzeURgaerFSBTu1GPE
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

(1) can be achieved by overwriting "new" on the class itself:
  class Foo
    class << self
      def new
        raise "Don't do that!"
      end
    end
  end
  class Bar < Foo
  end

  Foo.new #=3D> raises
  Bar.new #=3D> doesn't raise

By (2) you probably mean simple namespacing...

  module X
    class Y
    end
  end

  Y #=3D> raises NameError
  X::Y #=3D> that's it.

On Sun, 2010-11-28 at 19:15 +0900, Diego Virasoro wrote:
> Hello,
> for some code I am writing, I'd like to have a couple of abstract
> classes. However I am not very sure how to go about it in Ruby.
>=20
> Ideally all I would need is:
> 1) The class cannot be instantiated
> and/or
> 2) The class is not visible outside of the module it comes in
>=20
> What would be the canonical way to go about this in Ruby? Should I use
> a mix-in module?
>=20
> Ideally I would prefer to use a class since all the subclasses have a
> similar instantiation so I'd like to code it only once and use
> super(), but then the user himself may try to instantiate it breaking
> the whole "magic". :)
>=20
> Thank you
> Diego
>=20


--=-CAwzeURgaerFSBTu1GPE
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: This is a digitally signed message part

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.10 (GNU/Linux)
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=F2HX
-----END PGP SIGNATURE-----

--=-CAwzeURgaerFSBTu1GPE--