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POFactory method for generic interface
 

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  1. POFactory method for generic interface
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    <p>I think this code is mortally wounded but would like some opinions before I take a new approach. </p> <p>I am writing a factory method for the following interface.</p> <pre><code>public interface ITransformer&lt;I, O&gt; { O Transform(I input); } </code></pre> <p>Here is a possible implementation of the interface</p> <pre><code>public class CarToTruckTransformer : ITransformer&lt;Car, Truck&gt; { public Truck Transform(Car input) { Truck output = new Truck(); output.Seats = input.Seats - 2; output.BedSize = input.TrunkSize; output.Gunrack = true; return output; } } </code></pre> <p>The first factory I did looks like this</p> <pre><code>static class TransformerFactory { public static ITransformer&lt;I, O&gt; GetTransformer&lt;I, O&gt;() { if (typeof(I) == typeof(Car) &amp;&amp; typeof(O) == typeof(Truck)) { return (ITransformer&lt;I, O&gt;)new CarToTruckTransformer(); } else { return null; } } } </code></pre> <p>But I have to know the exact types when I call the factory method so it seems less than ideal.</p> <pre><code>ITransformer&lt;Car, Truck&gt; transf = TransformerFactory.GetTransformer&lt;Car, Truck&gt;(); </code></pre> <p>I have also toyed with the following, but I'm afraid this may be a gross misuse of the dynamic keyword.</p> <pre><code>public class TransformerFactory2 { public static dynamic GetTransformer(VehicleBase input, VehicleBase output) { if (input.GetType() == typeof(Car) &amp;&amp; output.GetType() == typeof(Truck)) { return (ITransformer&lt;Car, Truck&gt;)new CarToTruckTransformer(); } else { return null; } } } </code></pre> <p>But it does allow me to get the factory syntax that I want.</p> <pre><code>dynamic transf = TransformerFactory2.GetTransformer(car, truck); </code></pre> <p>I've also considered the first option but calling the factory method with reflection so I could dynamically assign the type variables.</p> <p>Ultimately, I would like the entire "transform" process to be contained in one reusable method and just implement new transformers when needed but I'm not there yet.<br> Is there a better or safer approach for this kind of situation?</p> <p>Thanks for reading.</p>
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    1. USjohnnysim
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    1. COThis is the kind of problem that is best solved by a dependency injection library like Ninject. These libraries allow you to easily bind concrete implementations to an interface and then your factory can easily get the proper implementation at execution time.
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      1. POFactory method for generic interface
      1. USAndrew Hare
 

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