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copied!<p>There is nothing magical going on. You are specifying concrete types, so naturally they are resolvable, because if we have the <code>Type</code> object, we can call a constructor on it.</p> <pre><code>class Fred { }; Fred f1 = new Fred(); Type t = typeof(Fred); Fred f2 = (Fred)t.GetConstructor(Type.EmptyTypes).Invoke(null); </code></pre> <p>The last line above is effectively what happens, the type t having been found by using <code>typeof</code> on the type parameter you give to <code>Resolve</code>.</p> <p>If the type cannot be constructed by new (because it's in some unknown separate codebase) then you wouldn't be able to give it as a type parameter to <code>Resolve</code>.</p> <p>In the second case, it is constructor injection, but it's still a known concrete constructable type. Via reflection, the Unity framework can get an array of all the Types of the parameters to the constructor. The type <code>TestWhatever</code> is constructable, so there is no ambiguity or difficulty over what to construct.</p> <p>As to your concern about separate modules (assemblies), if you move <code>TestWhatever</code> to another assembly, that will not change the lines of code you've written; it will just mean that you have to add a reference to the other assembly to get this one to build. And then <code>TestWhatever</code> is still an unambiguously refeferenced constructable type, so it can be constructed by Unity.</p> <p>In other words, if you can refer to the type in code, you can get a <code>Type</code> object, and so at runtime it will be directly constructable.</p> <p><strong>Response to comment:</strong></p> <p>If you delete the class <code>TestWhatever</code>, you will get a compile-time error, because you refer to that type in your code. So it won't be possible to get a runtime by doing that.</p> <p>The decoupling is still in effect in this arrangement, because you could register a specific instance of <code>TestWhatever</code>, so every call to <code>Resolve<TestWhatever>()</code> will get the same instance, rather than constructing a new one.</p>

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