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POCustom Guice Scope, or a better approach?
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  1. POCustom Guice Scope, or a better approach?
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    copied!<p>Here's my problem:</p> <p>It's first important to know that I'm writing a simulation. This is a standalone application, and is single-threaded. I have essentially two classes of objects that have different scoping requirements.</p> <ol> <li><p>Classes that should be used as singletons throughout the entire simulation. An instance of Random, as an example.</p></li> <li><p>Groups of classes that are created together, and within the group, each instance should be treated like a Singleton. For example, say <code>RootObject</code> is the top level class, and has a dependency to <code>ClassA</code> and <code>ClassB</code>, both of which have a dependency to <code>ClassD</code>. For any given <code>RootObject</code>, both of its dependencies (<code>ClassA</code> and <code>ClassB</code>) should depend on the same instance of <code>ClassD</code>. However, instances of <code>ClassD</code> should not be shared across different instances of <code>RootObject</code>.</p></li> </ol> <p>Hopefully that makes sense. I can think of two approaches to this. One is to mark all of the injected objects as Singletons, create the root injector, and spin off a child injector each time I need to create a new <code>RootObject</code> instance. Then, the instances of <code>RootObject</code> and all of its dependencies are created as Singletons, but that scoping information is thrown away the next time I go to create another <code>RootObject</code>.</p> <p>The second approach is to implement some type of custom scope.</p> <p>The Guice documentation gives conflicting advice... On one hand, it says that you should have a single injector, and that ideally it is called once to create some top level class. On the other hand, it says to stay away from custom scopes.</p>
 

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