From: Robert Klemme <bob.news@...>
Date: 2003-07-30T11:14:01+09:00
Subject: Re: Trouble with inherited


"Steve Tuckner" <STUCKNER@MULTITECH.COM> schrieb im Newsbeitrag
news:0c3a01c352d9$16fc9a20$6904a8c0@multitech.prv...
> In my case, I am interested in getting a string that would be specific
to
> that class (and not the class name). I am using this name as a hash key
from
> the name to the class.
>
> Now I can simply save the class in a list and then when the hash would
be
> used later, I can simply generate the hash at that time for each
request.
> This seems not as elegant but probably is not much of a real speed
penalty.
>
> Is there a better more elegant way of doing this?

Why don't you just do this?

class A
  @@subhash = {}

  def self.get(key)
    @@subhash[key]
  end
end

class B < A
  @@subhash["my key"]=self
end

A.get("my key")

Subclasses have to obey a certain convention anyway (i.e. providing the
key) so you might as well do it this way.

Otherwise you could do

class A
  class << self
    def inherited(subclass)
      (@subqueue||=[]) << subclass
    end

    def lookup(key)
      while ( @subqueue && cl = @subqueue.shift )
        (@subhash||={})[ cl.my_name ] = cl
      end

      @subhash && @subhash[key]
    end
  end
end

class B < A
 class << self
    def my_name
        "the B class"
    end
 end
end

A.lookup "the B class"

But I'd regard this a bit complicated.

    robert