我有一个对象,该对象采用项目的有序列表(IOrderedEnumerable),其中项目的顺序很重要.

public class OrderedListWorker : IListWorker
{
    private OrderedListWorker(IOrderedEnumerable<IListItem> orderedListItems)
    {
        foreach (var listItem in orderedListItems)
            listItem.DoSomethingWhereOrderMatters();
    }
}

我有多个IListItem类型的对象.

如何在Autofac中注册OrderedListWorker,并确保在运行时按特定顺序获取ListItems？

我看到This Post中不能保证订单,但是我不确定如何保证订单.

解决方法:

我有一个解决方案,它是IOrderedEnumerable和ResolveOrdered< TComponent>的组合.从我链接到上面的帖子中找到解决方案.

使用AutofacExtensions类：

public static class AutofacExtensions
{
    private const string OrderString = "WithOrderTag";
    private static int _orderCounter;

    public static IRegistrationBuilder<TLimit, TActivatorData, TRegistrationStyle>
        WithOrder<TLimit, TActivatorData, TRegistrationStyle>(
        this IRegistrationBuilder<TLimit, TActivatorData, TRegistrationStyle> registrationBuilder)
    {
        return registrationBuilder.WithMetadata(OrderString, Interlocked.Increment(ref _orderCounter));
    }

    public static IOrderedEnumerable<TComponent> ResolveOrdered<TComponent>(this IComponentContext context)
    {
        return
            context.Resolve<IEnumerable<Meta<TComponent>>>()
                   .OrderBy(m => m.Metadata[OrderString])
                   .Select(m => m.Value).OrderBy(c => true);
    }
}

我可以指定我的注册如下：

builder.RegisterType<ListItemA>().As<IListItem>().WithOrder();
builder.RegisterType<ListItemB>().As<IListItem>().WithOrder();
builder.RegisterType<OrderedListWorker>()
                   .As<IListWorker>()
                   .WithParameter(
                       new ResolvedParameter(
                           (info, context) => true,
                           (info, context) => context.ResolveOrdered<IListItem>()));