c# - .NET 2.0等效于C#扩展方法

Question

如何通过将扩展方法替换为等效的.NET 2.0来将这段代码更改为.NET 2.0兼容？

public interface IMessagingService {
    void sendMessage(object msg);
}
public interface IServiceLocator {
    object GetService(Type serviceType);
}
public static class ServiceLocatorExtenstions {
    //.NET 3.5 or later extension method, .NET 2 or earlier doesn't like it
    public static T GetService<T>(this IServiceLocator loc) {
        return (T)loc.GetService(typeof(T));
    }
}
public class MessagingServiceX : IMessagingService {
    public void sendMessage(object msg) {
        // do something
    }
}
public class ServiceLocatorY : IServiceLocator {
    public object GetService(Type serviceType) {
        return null; // do something
    }
}
public class NotificationSystem {
    private IMessagingService svc;
    public NotificationSystem(IServiceLocator loc) {
        svc = loc.GetService<IMessagingService>();
    }
}
public class MainClass {
    public void DoWork() {
        var sly = new ServiceLocatorY();
        var ntf = new NotificationSystem(sly);
    }
}

非常感谢你。

Answer 1

只需从扩展方法中删除this关键字即可。

public static class ServiceLocatorExtensions
{    
    public static T GetService<T>(IServiceLocator loc) {
        return (T)loc.GetService(typeof(T));
    }
}

并通过传递您要“扩展”的对象实例，将其作为其他任何静态方法调用：

IServiceLocator loc = GetServiceLocator();
Foo foo = ServiceLocatorExtensions.GetService<Foo>(loc);

实际上，这就是.Net 3.5编译器在后台执行的操作。顺便说一句后缀 Extensions您也可以删除。例如。使用 Helper不要混淆别人。