Re: Singleton Design pattern with a twist - n00b

From:

Patricia Shanahan <pats@acm.org>

Newsgroups:

comp.lang.java.programmer

Date:

Mon, 01 Jan 2007 09:23:30 GMT

Message-ID:

<mq4mh.5198$pQ3.2083@newsread4.news.pas.earthlink.net>

eladkatz@gmail.com wrote:

Arne Vajh?j wrote:

eladkatz@gmail.com wrote:

Hi all, i have a question about using the singleton DP in java.
say i want to make a debugger singleton, but i want to be able to pass
paramaters to it when it is first created.
that is - i want to pass a paramater i read called isDebugEnabled -
that decides in the loggers print method if i should print or not - how
can i pass it? should i pass it in the getInstance method or should i
use some kind of static member that has a default value and that is
changed directly?
i know that design-wise this isn't optimal and that it would be best if
the logger read the paramater itself and it wasn't passed to it,
however, this is not an option due to other design constaints...
i'd appreciate any help in this subject
thanks,

I would probably use something like:

private static ConfigInfo confinfo;
public static setup(ConfigInfo cfg) {
     if(instance == null) {
         confinfo = cfg;
     } else {
         throw VeryBadException("Too late !");
     }
}

Arne

thanks but the thing is - this means that whenever i get the singleton
(many places) i have to try/catch it and this will make my code very
hard to read and also much more complicated, there has to be a better
way...

Have you looked at java.util.logging? If not, I suggest doing so, to see
whether it meets your needs more simply than rolling your own.

Patricia