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copied!<p>This is an interesting problem. How can you dependency inject re-usable assemblies that do not have an entry point. <em>I would really like to see other people's answer.</em></p> <p>Dependency injection is the responsibility of the <em>entry-point assembly</em>. Yet, if you have a lot of classes and assemblies each needing DI, then it is possible that they are left-off for some classes/assemblies and the task becomes onerous.</p> <h1>Solution One</h1> <p>Using convention over configuration. You stick to a rule of class <code>Foo</code> implementing <code>IFoo</code>, etc. A lot of DI frameworks have the means to set it up using convention.</p> <h1>Solution two</h1> <p>Above solution does not solve all problems since sometimes you need to parameterise the setup of the injection. Here is how I have solved the problem (especially for those assemblies loaded by <strong>MEF</strong> and this is for <code>AutoFac</code>):</p> <p><strong>Created an interface <code>IIocInstaller</code> where container (or builder is passed)</strong></p> <pre><code>public interface IIocInstaller { void Setup(ContainerBuilder builder); } </code></pre> <p><strong>Created an assembly attribute that flags assemblies needing DI:</strong></p> <pre><code>[AttributeUsage(AttributeTargets.Assembly)] public class ExportAssemblyAttribute : Attribute { } </code></pre> <p><strong>In each assembly, I create a class that sets up DI:</strong></p> <pre><code>[assembly: ExportAssembly] namespace This.That { [Export(typeof(IIocInstaller))] public class IocInstaller : IIocInstaller { public void Setup(ContainerBuilder builder) { .... } } } </code></pre> <p>Then in the entry point, I have a common code which looks through all loaded assemblies (including MEFed ones) that have the assembly attribute and then look for the type implementing the <code>IIocInstaller</code> and then call Setup on them.</p>

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