工厂模式，返回一个通用类并有一个参数

Question

I have this implementation of Factory Pattern

public interface IFactory<T>
{
    T GetObject();
}

public class Factory<T> : IFactory<T> where T : new()
{
    public T GetObject()
    {
        return new T();
    }
}

But I'd like than GetObject return an instance of a generic class Repository<Customer> ( Repository implement IRepository ) and the factory has an argument (ISession type)

The result should be :

IRepository<ICustomer> myRepo = new Factory<ICustomer>(session);

How can I do this ?

Thanks,

Answer 1

Consider having a parameterless constructor instead, and some initialization function that takes the parameter. Other than not being able to pass a parameter through your factory, consider the case when you will want to deserialize your objects. They should be constructed and then the parameters should be filled one by one after that.

Answer 2

Does it have to be so generic? Why not like this?

public interface IFactory<T>
{
    IRepository<T> Create(ISession session);
}

public class RepositoryFactory<T> : IFactory<T> where T : new()
{
    public IRepository<T> Create(ISession session)
    {
        return new IRepository<T>();
    }
}

Answer 3

I'm not sure if you really need that level of generic but you can use generic fluent factory approach and have initialization function not from constructor instead.

  var CustomerGeneric = GenericFluentFactory<Customer, WebSession>
                        .Init(new Customer(), new WebSession())
                        .Create();


public static class GenericFluentFactory<T, U>
{
    public static IGenericFactory<T, U> Init(T entity, U session)
    {
        return new GenericFactory<T, U>(entity, session);
    }        
}

public class GenericFactory<T, U> : IGenericFactory<T, U>
{
    T entity;
    U session;

    public GenericFactory(T entity, U session)
    {
        this.entity = entity;
        this.session = session;
    }

    public T Create()
    {
        return this.entity;
    }
}