如何将对象转换为泛型类型？

Question

I have many classes that implements IBuilder<> interface such the ones below

UPDATED: each Model1, Model2... inherits from IModel

public class A : IBuilder<Model1>
{
     public Model1 Create(string param)
     {
         return new Model1();
     }
}
public class B : IBuilder<Model2>
{
     public Model2 Create(string param)
     {
          return new Model2();
     }
}

I'm using StructureMap to register all classes that inherit IBuilder<>

Scan(x =>
{
       x.TheCallingAssembly();
       x.AddAllTypesOf(typeof(IViewModelBuilder<>));                
});

UPDATED

Now, every time I need to get model of some Module I call Do function

public IModel Do(Module module)
{
        //ModelSettings is taken from web.config  
        var builderType = Type.GetType(string.Format("{0}.{1}ModelBuilder,{2}", ModelSettings.Namespace, module.CodeName, ModelSettings.Assembly));
        var builder = ObjectFactory.GetInstance(t) as IViewModelBuilder<>;

        return builder.Create("");            
}

I get compilation error in the line ObjectFactory.GetInstance(t) as IViewModelBuilder<> . Many posts suggest to create NOT generic interface(IViewModelBuilder) and let the generic one to inherit it. And then I could make the casting like

ObjectFactory.GetInstance(t) as IViewModelBuilder

Is this the only way?

Thank you

Answer 1

Your code for Do and GetInstance should be generic too. Basicly it could look something like this

public T Do<T> ()
{
     return ObjectFactory.GetInstance<T>().Create();
}

Answer 2

Couldn't you make Do() generic?

var m = Do<B>();

public T Do<T>()
{ 
   var builder = (IViewModelBuilder<T>)ObjectFactory.GetInstance(typeof(T));
   return builder.Create("");
}

If you can't, using non-generic interface is probably your best bet, but there are other options like using reflection or C# 4's dynamic :

var m = Do(typeof(B));

public object Do(Type t)
{ 
   dynamic builder = ObjectFactory.GetInstance(t);
   return builder.Create("");
}

Answer 3

The only thing I can think of is that you make an interface or a base class that your viewmodel inherit from. Ie:

public class Model1 : ModelBase
{
}

public class ModelBase
{
}

public ModelBase Do(Type t)
{
    var builder = ObjectFactory.GetInstance(t);
    return t.GetMethod("Create").Invoke(builder, new object[] { "" }) as ModelBase;
}

Answer 4

You need to introduce a non-generic IViewModelBuilder interface if you want to call it in a non-generic scenario. The generic IViewModelBuilder<T> would implement IViewModelBuilder .

The only other alternative is to invoke the create method via reflection, but I don't see why that would be preferred:

var builder = ObjectFactory.GetInstance(builderType);
var method = builderType.GetMethod("Create");
return (IModel) method.Invoke(builder, new[]{""});