Can I use a type from reflection as a type parameter?

Question

Can I use a type from reflection as a type parameter? E.g. I want to pick a persister based on a passed object:

IPersister GetPersisterFor(IEntity entity)
{
    return GetPersisterFor<entity.GetType()>(); // <-- this cannot be compiled
}

IPersister GetPersisterFor<TEntity>() where TEntity : IEntity
{
    //some logic to get persister...
}

Answer 1

Only via reflection; you would need to use GetMethod to get the MethodInfo for the generic method, then call MakeGenericMethod(entity.GetType()).Invoke(this, null); on that.

However, easier is to cheat via dynamic:

IPersister Evil<T>(T obj) where T : IEntity {
    return GetPersisterFor<T>();
}

And make the first method just:

return Evil((dynamic)entity);

This is then a dynamic expression which will detect the correct T to use (to call Evil-of-T) for you.

Note: the only reason you need an extra method is to make sure it doesn't resolve back to itself recursively, since the names are the same.