带有临时接口的运行时多重继承

Question

我正在尝试使用临时接口让运行时多重继承工作，但是当我想将对象传递给方法时我遇到了困难。

public interface IEngine {
    void Foo();
}

public interface IWheels {
    void Foo();
}

public interface IChassie {
    void Foo();
}

public interface IPaintShop {
    void PaintWheels(IWheels wheels);
    void PaintChassie(IChassie chassie);
    void ChromeEngine(IEngine engine);
}

var paintShop = Impromptu.ActLike<IPaintShop>();
var car = Impromptu.ActLike(new [] {typeof(IEngine), typeof(IWheels), typeof(IChassie) } ); 
// dynamic car = Impromptu.ActLike(new [] {typeof(IEngine), typeof(IWheels), typeof(IChassie) } ); // Same error 
paintShop.PaintWheels(car); // RuntimeException as car is dynamic and not the expected IWheels

Microsoft.CSharp.RuntimeBinder.RuntimeBinderException : The best overloaded method match for 'MyStuff.PaintWheels(IWheels)' has some invalid arguments

我试过投射但得到 InvalidCastException:

paintShop.PaintWheels((IWheels)car);

System.InvalidCastException : Unable to cast object of type 'ImpromptuInterface.ActLikeCaster' to type 'MyStuff.IWheels'.

下面的方法可行，但我不确定这是正确的方法；当 IWheels 接口应该已经被继承时，将 car 转换为 IWheels 似乎是没有根据的：

var wheels = Impromptu.CoerceConvert(car, typeof (IWheels));
paintShop.PaintWheels(wheels);

使用即兴接口实现运行时多重继承的正确方法是什么？

Answer 1

您运行遇到的问题都与类型安全有关——即使在使用像 Impromptu 这样的库时，您也必须确保编译器和运行时确保您传递给方法是方法需要的类型。

ActLike<T> 可以实现许多接口，但它只是 returns T 的单个类型实例，因此如果没有类型告诉编译器您的实例实现了多个接口，您将被迫投射到必要的接口。

此外，ImpromptuInterface 允许您 wrap 具有与该对象的实现非正式匹配的接口的对象，即使该接口未正式声明也是如此。作为该库的使用者，您仍然必须提供要包装的库的实现。

尝试如下操作：

using System;
using ImpromptuInterface;
using ImpromptuInterface.Dynamic;

namespace Example
{
    public interface IEngine
    {
        void Foo();
    }

    public interface IWheels
    {
        void Foo();
    }

    public interface IChassie
    {
        void Foo();
    }

    public interface IPaintShop
    {
        void PaintWheels(IWheels wheels);
        void PaintChassie(IChassie chassie);
        void ChromeEngine(IEngine engine);
    }

    internal class Program
    {
        public static void Main(string[] args)
        {
            var ps = new
            {
                PaintWheels = ReturnVoid.Arguments<IWheels>(wheels => wheels.Foo()),
                PaintChassie = ReturnVoid.Arguments<IChassie>(chassie => chassie.Foo()),
                ChromeEngine = ReturnVoid.Arguments<IEngine>(engine => engine.Foo())
            };
            var paintShop = ps.ActLike<IPaintShop>();

            var fullCar = new
            {
                Foo = ReturnVoid.Arguments(() => Console.WriteLine("Hello World!"))
            };

            var car = fullCar.ActLike<IEngine>(typeof(IChassie),typeof(IWheels));

            //each of these 3 calls prints "Hello World!" to the console
            paintShop.PaintWheels((IWheels)car);//need to tell the compiler to cast your car to type IWheels because var car is of type IEngine
            paintShop.PaintChassie(car as IChassie);//need to tell the compiler to cast your car to type IChassie because var car is of type IEngine
            paintShop.ChromeEngine(car);//works sans cast because var car is of type IEngine

            //each of these 3 calls prints "Hello World!" to the console, too
            dynamic dynamicCar = car;
            paintShop.PaintWheels(dynamicCar);//by using dynamic you disable the compile time
            paintShop.PaintChassie(dynamicCar);//type checking and the compiler "trusts you" on the typing
            paintShop.ChromeEngine(dynamicCar);//since Impromptu wrapped your object and implemented the interfaces for you, there is no runtime exception

            Console.ReadLine();
        }
    }
}

带有临时接口的运行时多重继承

Runtime multiple inheritance with impromptu-interface

c#

inheritance

runtime

multiple-inheritance

impromptu-interface