Re: Looking for a pattern

=?ISO-8859-1?Q?Arne_Vajh=F8j?= <>
Wed, 31 Oct 2007 22:33:17 -0400
Bilz wrote:


I am looking for a good pattern. I have a rather large software app
that makes use of a service manager for its many services...
configuration, colors, data lookup, units, etc. Up until now the
service manager has been a singleton and anyone who wants access to a
service just asks the singleton.

Now we have a new requirement... run multiple instances of the
software in the same application space with different configurations.

So, now I need to think about a good design pattern to help me here.
I can only come up with two awkward options:

1. Pass a service manager key to every constructor of every class that
needs access to the service manager. The class can go to a singleton
to ask for the instance of the service manager by key. This is
awkward and I don't like it.

2. Create an interface for getting a service, and have every object in
the object tree implement the interface. Pass a "parent" object
reference to the "child" and implement the interfaces so they climb
the tree all the way to the root node to get an instance of the
service manager stored in the root node. This is better, but still

Is there a better design pattern out there to do what I need? I am
using .NET C#, though it shouldn't matter too much (unless .NET
already has a service I can leverage).

I would prefer solution #1 over #2. Much more flexible.

As a long time solution that seems obvious.

For a dirty hack: if the two instances of the software are actually
running in different threads, then you could register each thread to
a given instance of the software and have the singleton create
based on thread.


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