类属性定义为实现接口的对象

Question

I have a set of POCO classes which implement IConnectable and IEntity .

In one of the classes, Connection , I want two properties that are defined as objects that implement IConnectable .

    public interface IConnectable
{
 string Name { get; set; }
 string Url { get; set; }
}

And my connection class

    public partial class Connection : IEntity
{
    public int Id { get; set; }
    public T<IConnectable> From { get; set; }
    public T<IConnectable> To { get; set; }
    public ConnectionType Type { get; set; }
    public double Affinity { get; set; }
    public DateTimeOffset CreatedOn { get; set; }
}

I know I can't use generic objects are properties -- so is there any other way to do this?

Answer 1

It's most likely appropriate to just not have generics at all :

public partial class Connection : IEntity
{
    public int Id { get; set; }
    public IConnectable From { get; set; }
    public IConnectable To { get; set; }
    public ConnectionType Type { get; set; }
    public double Affinity { get; set; }
    public DateTimeOffset CreatedOn { get; set; }
}

If it's important that instances of Connection return types of something more derived then you'll need to make the whole class generic:

public partial class Connection<T> : IEntity
    where T : IConnectable 
{
    public int Id { get; set; }
    public T From { get; set; }
    public T To { get; set; }
    public ConnectionType Type { get; set; }
    public double Affinity { get; set; }
    public DateTimeOffset CreatedOn { get; set; }
}

If you need to be able to have two different IConnectable types for the two properties, then you need to generic parameters:

public partial class Connection<TFrom, TTo> : IEntity
    where TFrom : IConnectable 
    where TTo : IConnectable 
{
    public int Id { get; set; }
    public TFrom From { get; set; }
    public TTo To { get; set; }
    public ConnectionType Type { get; set; }
    public double Affinity { get; set; }
    public DateTimeOffset CreatedOn { get; set; }
}