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POResolve automatic factory from named registration for generic type
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  1. POResolve automatic factory from named registration for generic type
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    copied!<ol> <li><p>Assume a simple interface:</p> <pre><code>public interface ICommandHandler&lt;T&gt; { void Handle(T command); } </code></pre></li> <li><p>Assume several implementations for different concrete <code>T</code>s like:</p> <pre><code>public class FooCommandHandler : ICommandHandler&lt;FooCommand&gt; { /*...*/ } </code></pre></li> <li><p>Assume a generic factory implementation of that interface:</p> <pre><code>public class FactoryCommandHandler&lt;T&gt; : ICommandHandler&lt;T&gt; { public FactoryCommandHandler(Func&lt;ICommandHandler&lt;T&gt;&gt; factory) { /*...*/ } /*...*/ } </code></pre></li> </ol> <p>Now, I want to register the factory handler from <em>3</em> to be the instance that is resolved when an <code>ICommandHandler&lt;T&gt;</code> is resolved.<br> My problem is that I fail to correctly register the other implementations so a factory for them can be resolved.</p> <p>Here is what I tried:</p> <pre><code>builder.RegisterAssemblyTypes(assembly) .Where(type =&gt; type.Name.EndsWith("CommandHandler")) .Named("concreteCommandHandler", typeof(ICommandHandler&lt;&gt;)); builder.RegisterGeneric(typeof(FactoryCommandHandler&lt;&gt;) .WithParameter( (p, c) =&gt; true, (p, c) =&gt; c.ResolveNamed("concreteCommandHandler", p.ParameterType)) .As(typeof(ICommandHandler&lt;&gt;)); </code></pre> <p>However, this fails, because there is no named <code>Func&lt;ICommandHandler&lt;SomeConcreteCommand&gt;&gt;</code> registered. Autofac seems to be unable to automatically create a factory in this case, <a href="http://code.google.com/p/autofac/wiki/DelegateFactories" rel="nofollow">which it normally supports</a>.</p> <p>How to fix the registration and achieve my goal?</p>
 

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