From: Konrad Meyer <konrad@...>
Date: 2007-11-19T06:43:38+09:00
Subject: Re: [QUIZ] Goedel (#147)

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Quoth Eric Lavigne:
> On Nov 18, 2007 3:42 PM, steve <oksteev@yahoo.com> wrote:
> > there's an instance var @primes which has the list of already generated
> > primes, @primes.last would do it
> >
>=20
> Sounds simple enough, but accessing instance variables seems to be a
> rather verbose operation.
>=20
> Here is what it should look like (if the Prime class worked the way I
> originally expected):
>    primes =3D Prime.new
>    primes.next.doSomething
>    primes.last.doSomethingElse
>=20
> Here was my first attempt using your suggestion, which looks
> reasonable but doesn't work.
>    primes =3D Prime.new
>    primes.next.doSomething
>    primes.@primes.last.doSomethingElse
>=20
> Here is what finally worked, but I can't believe the verbosity of the
> final line. Is there a shorter way?

yes.

>    primes =3D Prime.new
>    primes.next.doSomething
>    primes.instance_variable_get("@primes").last.doSomethingElse

Instead of doing that, you could just extend the Prime class:

  class Prime
    def this
      @primes.last
    end
  end

  primes =3D Prime.new
  primes.next.doSoemthing
  primes.this.doSomethingElse

That should work how you want, yes?

>=20
> --=20
> There are two ways of constructing a software design: One way is to
> make it so simple that there are obviously no deficiencies, and the
> other way is to make it so complicated that there are no obvious
> deficiencies. The first method is far more difficult.
>=20
>                     - C.A.R. Hoare -
>=20

HTH,
=2D-=20
Konrad Meyer <konrad@tylerc.org> http://konrad.sobertillnoon.com/

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