From: Robert Klemme <bob.news@...>
Date: 2005-08-31T17:26:23+09:00
Subject: Re: More elegant replacement for global variables

Michael wrote:
> I'm playing around with a ruby app using XML-RPC. Currently I'm using
> global variables so I can create multiple objects without having to
> log
> in for each and every object.
>
> class Base
> def initialize(user, pass)
> $user, $pass = user, pass
> end
>
> def login()
> $client = XMLRPC::Client.new(...)
> $sessionid = $client.call("xmlrpc.method", $user, $pass)
> return $sessionid
> end
> end
>
> Derived classes look like this:
>
> class Object1 < Base
> def initialize()
> if not $sessionid then self.login end
> end
> end
>
> This way I can log in once with the first object created without
> having
> to log in each time. However, this seems inelegant to me. Is there a
> more elegant, or just more rubyish, way of doing this? Also, I'd have
> potential problems if I wanted to log on as multiple users.
>
> Would it make more sense just to pass around an instance of the Base
> object:
>
> class Object2
> def initialize(xmlrpc_client)
> if not xmlrpc_client.sessionid then xmlrpc_client.login
> end
>
> def call_xmlrpc_method(method, params)
> results = xmlrpc_client.call(method, params)
> return results
> end
> end
>
> xmlrpc_client = Base.new
> o2 = Object2.new(xmlrpc_client)
>
> Pro: no global variables. Con: coupling between Object2 and Base
> classes. --Michael

Although your scenario is not fully clear to me, I'd have a session
instance that stores all session related information.  Also I would not
have your classes (Object1) inherit the session class but instead pass it
around.

Kind regards

    robert