尝试了解 IoC（使用 Autofac）中的生命周期范围意味着什么？

Question

起初我私下认为我可以理解它，但是通过Autofac的一些简单示例，看来我可能理解错了，这是我试过的代码：

//register the service
autofacBuilder.RegisterType<MyService>()
              .As<IMyService>().InstancePerLifetimeScope();
//testing code
void _test1()
{
   var myService = autofacContainer.Resolve<IMyService>();
}
void _test2()
{
    _test1();
    var myService = autofacContainer.Resolve<IMyService>();
}

通过运行_test2()测试，您可以简单地检查2种方法中解析的实例。

所以通过上面的代码，我理解 _test1 中的 myService 和 _test2 中的 myService 应该是不同的。因为我认为 _test1 中 myService 的生命周期范围应该在那个方法中，而 _test2 中 myService 的生命周期范围也应该在 _test2 中.所以我们这里有2个不同的作用域，但是myService的解析实例是同一个

那么请您向我解释一下这个问题，lifetime scope 在这里到底是什么意思？在同一个 class 内？或者更大的东西？

Answer 1

你搞糊涂了c# scopes and autofac's scopes。这就像比较苹果和栅栏。 :) 它们只是不同而已，彼此没有任何关系。

因此，为了阐明它，请查看下面的基本示例。请注意，如果您是像示例 1 中那样启动它们的人，那么实际上您应该销毁这些范围。在其他示例中，为简洁起见，我跳过了它。

// example 1
autofacBuilder.RegisterType<MyService>().As<IMyService>().InstancePerLifetimeScope();
var container = autofacBuilder.Build();

void _test1(IComponentContext scope){
    var myService = scope.Resolve<IMyService>();
}

void _test2(IComponentContext scope){
    // the same scope is used here and in _test1()
    // this means that the service instance will be the same here and there
    _test1(scope);
    var myService = scope.Resolve<IMyService>();
}

// it's only here that DI lifetime scope starts
using (var scope = container.BeginLifetimeScope()) {
    _test2(scope);
}



// example 2
autofacBuilder.RegisterType<MyService>().As<IMyService>().InstancePerLifetimeScope();
var container = autofacBuilder.Build();

void _test1(IComponentContext scope){
    var myService = scope.Resolve<IMyService>();
}

void _test2(IComponentContext scope){
    // now new scope is used in _test1() call
    // this means that instances will be different here and there since they are resolved from different scopes
    _test1(scope.BeginLifetimeScope());
    var myService = scope.Resolve<IMyService>();
}

var scope = container.BeginLifetimeScope();
_test2(scope);



// example 3
// NOTE THIS!
autofacBuilder.RegisterType<MyService>().As<IMyService>().InstancePerDependency();
var container = autofacBuilder.Build();

void _test1(IComponentContext scope){
    var myService = scope.Resolve<IMyService>();
}

void _test2(IComponentContext scope){
    // the same scope is used here and in _test1()
    // but now service instances will be different even though they are resolved from the same scope
    // since registration directs to create new instance each time the service is requested.
    _test1(scope);
    var myService = scope.Resolve<IMyService>();
}

var scope = container.BeginLifetimeScope();
_test2(scope);



// example 4
autofacBuilder.RegisterType<MyService>().As<IMyService>().SingleInstance();
var container = autofacBuilder.Build();

void _test0(IComponentContext scope){
    var myService = scope.Resolve<IMyService>();
}

void _test1(IComponentContext scope){
    _test0(scope.BeginLifetimeScope());
    var myService = scope.Resolve<IMyService>();
}

void _test2(IComponentContext scope){
    // all the scopes used here and in other calls are different now
    // but the service instance will be the same in all of them even though it is requested from different scopes
    // since registration directs to get the same instance each time the service is requested regardless of the lifetime scope.
    _test1(scope.BeginLifetimeScope());
    var myService = scope.Resolve<IMyService>();
}

var scope = container.BeginLifetimeScope();
_test2(scope);

尝试了解 IoC（使用 Autofac）中的生命周期范围意味着什么？

Try to understand what lifetime scope means in IoC (with Autofac)?

c#

dependency-injection

inversion-of-control

autofac

lifetime-scoping