每个匹配的生命周期范围的实例，默认情况下? [英] Instance per matching lifetime scope, with default?

问题描述

我想在 Autofac 中为每个匹配的生命周期范围注册一个实例，但偶尔需要从全局容器(没有匹配的生命周期范围)请求一个实例.在不存在匹配的生命周期范围的场景中，我想给出一个顶级实例而不是抛出异常.

I'd like to have an instance per matching lifetime scoped registration in Autofac, but occasionally need to request an instance from a global container (where there is no matching lifetime scope). In scenarios where no matching lifetime scope exists, I want to give a top-level instance instead of throwing an exception.

这可能吗?

推荐答案

我认为您最好通过引入新的生命周期选项来扩展 Autofac.我采用了 Autofac 源并对其进行了一些修改:

I think you'd better extend Autofac by introducing a new lifetime option. I took the Autofac sources and modified them a bit:

public static class RegistrationBuilderExtensions
{
    public static IRegistrationBuilder<TLimit, TActivatorData, TRegistrationStyle> InstancePerMatchingOrRootLifetimeScope<TLimit, TActivatorData, TRegistrationStyle>(this IRegistrationBuilder<TLimit, TActivatorData, TRegistrationStyle> builder, params object[] lifetimeScopeTag)
    {
        if (lifetimeScopeTag == null) throw new ArgumentNullException("lifetimeScopeTag");
        builder.RegistrationData.Sharing = InstanceSharing.Shared;
        builder.RegistrationData.Lifetime = new MatchingScopeOrRootLifetime(lifetimeScopeTag);
        return builder;
    }
}

public class MatchingScopeOrRootLifetime: IComponentLifetime
{
    readonly object[] _tagsToMatch;

    public MatchingScopeOrRootLifetime(params object[] lifetimeScopeTagsToMatch)
    {
        if (lifetimeScopeTagsToMatch == null) throw new ArgumentNullException("lifetimeScopeTagsToMatch");

        _tagsToMatch = lifetimeScopeTagsToMatch;
    }

    public ISharingLifetimeScope FindScope(ISharingLifetimeScope mostNestedVisibleScope)
    {
        if (mostNestedVisibleScope == null) throw new ArgumentNullException("mostNestedVisibleScope");

        var next = mostNestedVisibleScope;
        while (next != null)
        {
            if (_tagsToMatch.Contains(next.Tag))
                return next;

            next = next.ParentLifetimeScope;
        }

        return mostNestedVisibleScope.RootLifetimeScope;
    }
}

只需将这些类添加到您的项目并将您的组件注册为:

Just add these classes to your project and register you component as:

builder.RegisterType<A>.InstancePerMatchingOrRootLifetimeScope("TAG");

我自己没试过，但应该可以.

I haven't tried it myself, but it should work.

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